This at all events is certain, that eggs are very readily shaken and

injured when the fowls are disturbed during incubation, at which time

the fluids are liquefied and expanded, and their containing membranes

are distended and extremely tender.

EXERCISE THE EIGHTEENTH.

_The fourth inspection of the egg._

“In the course of the fifth day of incubation,” says Aristotle,[186]

“the body of the chick is first distinguished, of very small dimensions

indeed, and white; but the head conspicuous and the eyes extremely

prominent, a state in which they afterwards continue long; for they only

grow smaller and shrink at a later period. In the lower portion of the

body there is no rudimentary member corresponding with what is seen in

the upper part. But of the channels which proceed from the heart, one

now tends to the investing membrane, the other to the yelk; together

they supply the office of an umbilical cord. The chick, therefore,

derives its origin from the albumen, but it is afterwards nourished by

the yelk, through the umbilicus.”

These words of Aristotle appear to subdivide the entire generation of

the chick into three stages or periods, viz.: from the first day of the

incubation to the fifth; from thence on to the tenth or fourteenth: and

from this or that to the twentieth. It seems as if he had only given an

account in his history of the circumstances he observed at these three

epochs; and it is then indeed that the greatest changes take place in

the egg; as if these three critical seasons, or these three degrees in

the process which leads from the perfect egg to the evolution of the

chicken, were especially to be distinguished. On the fourth day the

first particle of the embryo appears, viz.: the punctum saliens and the

blood; and then the new being is incorporated. On the seventh day the

chick is distinguished by its extremities, and begins to move. On the

tenth it is feathered. About the twentieth it breathes, chirps, and

endeavours to escape. The life of the egg, up to the fourth day, seems

identical with that of plants, and can only be accounted as of a

vegetative nature. From this onwards to the tenth day, however, like an

animal, it is possessed by a sensitive and motive principle, with which

it continues to increase, and is afterwards gradually perfected,

becoming covered with feathers, furnished with a beak, nails, and all

else that is necessary to its escape from the shell; emancipated from

which, it enters at length on its own independent existence.

Of the incidents that happen after the fourth day, Aristotle enumerates

three particularly, viz.: the construction of the body; the distribution

of the veins, which have already the office and nature of the umbilicus;

and the matter whence the embryo first arises, and is constituted and

nourished.

In reference to the structure of the body, he speaks of its size and

colour, of the parts which are most conspicuous in it, (the head and

eyes,) and of the distinction of its extremities.

The body is indeed extremely minute, and of the form of the common

maggot that gives birth to the fly; it is of a white colour, too, like

the maggot of the flesh-fly which we see cherished and nourished in

putrid meat. He happily adds, “it is most remarkable for its head and

eyes.” For what first appears is homogeneous and indistinct, a kind of

concretion or coagulation of the colliquament, like the jelly prepared

from hartshorn; it is a mere transparent cloud, and scarcely

recognizable, save as it appears, divided, seemingly, into two parts,

one of which is globular and much larger than the other; this is the

rudiment of the head, which first becomes visible on the fifth day, very

soon after which the eyes are distinguishable, being from the first of

large size and prominent, and marked off from the rest of the head and

body by a certain circumfusion of black matter. Either of the eyes is

larger than the whole of the rest of the head, in the same way as the

head surpasses the remainder of the body in dimensions. The whiteness of

the body, and prominence of the eyes, (which, as well as the brain, are

filled internally with perfectly pellucid water, but externally are of a

dark colour), continue for some time--up to the tenth day, and even

longer; for, as we have seen, Aristotle says that “the eyes decrease at

a late period, and contract to the proper proportion.” But for my own

part, I do not think that the eyes of birds ever contract in the same

ratio which we observe between the head and eyes of a viviparous animal.

For if you strip off the integuments from the head and eyes of a fowl or

another bird, you will perceive one of the eyes to equal the entire

brain in dimensions; in the woodcock and others, one of the eyes indeed

is as large as the whole head, if you make abstraction of the bill. But

this is common to all birds that the orbit or cavity which surrounds the

eye is larger than the brain, a fact that is apparent in the cranium of

every bird. Their eyes, however, are made to look smaller, because every

part, except the pupil, is covered with skin and feathers; neither are

they possessed of such a globular form as would cause them to project;

they are of a flatter configuration, as in fishes.

“In the lower part of the body,” says the philosopher, “we perceive the

rudiments of no member corresponding with the superior members.” And the

thing is so in fact; for as the body at first appears to consist of

little but head and eyes, so inferiorly there is neither any

extremity,--wings, legs, sternum, rump,--nor any viscus apparent; the

body indeed is still without any kind of proper form; in so far as I am

able to perceive, it consists of a small mass adjacent to the vein, like

the bent keel of a boat, like a maggot or an ant, without a vestige of

ribs, wings, or feet, to which a globular and much more conspicuous mass

is appended, the rudiment of the head, to wit, divided, as it seems,

into three vesicles when regarded from either side, but in fact

consisting of four cells, two of which, of great size and a black

colour, are the rudiments of the eyes; of the remaining two one being

the brain, the other the cerebellum. All of these are full of perfectly

limpid water. In the middle of the blackness of the eye, the pupil is

perceived shining like a transparent central spark or crystal. I imagine

that three of these vesicles being particularly conspicuous, has been

the cause of indifferent observers falling into error. For as they had

learned from the schoolmen that there was a triple dominion in the

animal body, and they believed that these principal parts, the brain,

the heart, and the liver, performed the highest functions in the

economy, they easily persuaded themselves that these three vesicles were

the rudiments and commencements of these parts. Coiter, however, as

becomes an experienced anatomist, affirms more truly that whilst he had

observed the beak and eyes from the seventh day of incubation, he could

yet discover nothing of the viscera.

But let us hear the philosopher further: “Of the conduits which lead

from the heart, one tends to the investing membrane, another to the

yelk, in order to perform the office of umbilicus.” The embryo having

now taken shape, these veins do indeed perform the function of the

umbilical cord, the ramifications of one of them proceeding to be

distributed to the outer tunic which invests the albumen, those of the

other running for distribution to the vitellary membrane and its

included fluid. Whence it clearly appears that both of these fluids are

alike intended for the nourishment of the embryo. And although Aristotle

says that “the chick has its commencement in the albumen, and is

nourished through the umbilicus by the yelk,” he still does not say that

the chick is formed from the albumen. The embryo, in fact, is formed

from that clear liquid which we have spoken of under the name of the

colliquament, and the whole of what we have called the eye of the egg is

contained or included within the albumen. Neither does our author say

that the whole and sole nutriment of the embryo reaches it through the

umbilicus. My own observations lead me to interpret his words in this

way: although the embryo of the fowl begins to be formed in the albumen,

nevertheless it is not nourished solely by that, but also by the yelk,

to which one of the two umbilical conduits pertains, and from whence it

derives nourishment in a more especial manner; for the albumen,

according to Aristotle’s opinion, is the more concoct and purer liquid,

the yelk the more earthy and solid one, and, therefore, more apt to

sustain the chick when it has once attained to greater consistency and

strength; and further because, as shall be explained below, the yelk

supplies the place of milk, and is the last part that is consumed, a

residuary portion, even after the chick is born, and when it is

following its mother, being still contained in its abdomen.

What has now been stated takes place from the fourth to the tenth day. I

have yet to speak of the order and manner in which each of the

particulars indicated transpires.

In the inspection made on the fifth day, we observed around the short

vein which proceeds from the angle where the two alternately pulsating

points are situated, something whiter and thicker, like a cloud,

although still transparent, through which the vein just mentioned is

seen obscurely, and as it were through a haze. The same thing I have

occasionally seen in the more forward eggs in the course of the fourth

day. Now this is the rudiment of the body, and from hour to hour it goes

on increasing in compactness and solidity; both surrounding the

afore-named vein, and being appended to it in the guise of a kind of

globule. This globular rudiment far exceeds the coronal portion, as I

shall call it, of the vermicular body; it is triangular in figure, being

obscurely divided into three parts, like so many swelling buds of a

tree. One of these is orbicular and larger than either of the other two;

and it is darkened by most delicate filaments proceeding from the

circumference to the centre; this appears to be the commencement of the

ciliary body, and therefore proclaims that this is the part which is to

undergo transformation into the eye. In its middle the minute pupil,

shining like a bright point, as already stated, is conspicuous; and it

was from this indication especially that I ventured to conjecture that

the whole of the globular mass was the rudiment of the future head, and

this black circle one of the eyes, having the other over against it; for

the two are so situated that they can by no means be seen at once and

together, one always lying over and concealing the other.

The first rudiment of the future body, which we have stated to sprout

around the vein, acquires an oblong and somewhat bent figure, like the

keel of a boat. It is of a mucaginous consistence, like the white mould

that grows upon damp things excluded from the air. The vein to which

this mucor attaches, as I have said, is the vena cava, descending along

the spinal column, as my subsequent observations have satisfied me. And

if you carefully note the order of contraction in the pulsating

vesicles, you may see the one which contracts last impelling its blood

into the root of this vein and distending it.

Thus there are two manifest contractions and two similar dilatations in

the two vesicles which are seen moving and pulsating alternately; and

the contraction of the one which precedes causes the distension or

dilatation of the other; for the blood escapes from the cavity of the

former vesicle, when it contracts, into that of the latter, which it

fills, distends, and causes to pulsate; but this second vesicle,

contracting in its turn, throws the blood, which it had received from

the former vesicle, into the root of the vein aforesaid, and at the same

time distends it.--I go on speaking of this vessel as a vein, though

from its pulsation I hold it to be the aorta, because the veins are not

yet distinguished from the arteries by any difference in the thickness

of their respective coats.

After having contemplated these points with great care, and in many

eggs, I remained for some time in suspense as to the opinion I should

adopt; whether I should conclude that the concrete appended globular

mass proceeded from the colliquament in which it swam, becoming a

compacted and coagulated matter in the way that clouds are formed from

invisible vapour condensed in the upper regions of the air; or believe

that it took its rise from a certain effluvium exhaled from the

sanguineous conduit mentioned, originating by diapedesis or

transudation, and by deriving nourishment from thence, was enabled to

increase? For the beginnings of even the greatest things are often

extremely small, and, by reason of this minuteness, sufficiently

obscure.

This much I think I have sufficiently determined at all events, viz.

that the puncta salientia and meatus venosi, and the vena cava itself,

are the parts that first exist; and that the globular mass mentioned

afterwards grows to them. I am further certain that the blood is thrown

from the punctum saliens into the vein, and that from this does the

corpuscle in question grow, and by this is it nourished. The fungus or

mucor first originates from an effluvium of the vein on which it

appears, and it is thence nourished and made to increase; in the same

way as mouldiness grows in moist places, in the dark corners of houses

which long escape cleansing; or, like camphor upon cedar wood tables,

and moss upon rocks and the bark of trees; lastly, as a kind of delicate

down grows upon certain grubs.

Upon the same occasion I also debated with myself whether or not I

should conclude, that with the coagulation of the colliquament

accomplished, the rudiments of the head and body existed simultaneously

with the punctum saliens and the blood, but in a pellucid state, and so

delicate that they almost escaped the eye, until becoming inspissated

into a fungus or mucor, they acquired a more opaque white colour, and

then came into view; the blood meantime from its greater spissitude and

purple colour being readily perceptible in the diaphanous colliquament.

But now when I look at the thing more narrowly, I am of opinion that the

blood exists before any particle of the body appears; that it is the

first-born of all the parts of the embryo; that from it both the matter

out of which the fœtus is embodied, and the nutriment by which it grows

are derived; that it is in fine, if such thing there be, the primary

generative particle. But wherefore I am led to adopt this idea shall

afterwards be shown more at length when I come to treat of the primary

genital part, of the innate heat, and the radical moisture; and, at the

same time, conclude as to what we are to think of the vital principle

(anima), from a great number of observations compared with one another.

About this period almost every hour makes a difference; every thing

grows larger, more definite and distinct; the rate of change in the egg

is rapid, and one change succeeds immediately upon the back of another.

The cavity in the egg is now much larger, and the whole of its upper

portion is empty; it is as if a fifth part of the egg had been removed.

The ramifications of the veins extend more widely, and are more

numerous, not only in the colliquament as before, but they spread on one

hand into the albumen, and on the other into the yelk, so that both of

these fluids are everywhere covered over with blood-vessels. The upper

portion of the yelk has now become much dissolved, so that it very

obviously differs from the lower portion; there are now, as it were, two

yelks, or two kinds of yelk; whilst the superior, like melted wax, is

expanded and looks pellucid, the inferior has become more dense, and

with the thicker portion of the albumen has subsided to the sharp end of

the egg. The tunica propria of the upper portion of the yelk is so thin

that it gives way on the slightest succussion, when there ensues

admixture of the fluids, and, as we have said, interruption to the

further progress of the process of generation.

And now it is that the rudiments of the embryo first become conspicuous,

as may be seen in the fifth and sixth figure of Fabricius; the egg being

put into fair water it will be easy to perceive what parts of the body

are formed, what are still wanting. The embryo now presents itself in

the form of a small worm or maggot, such as we encounter on the leaves

of trees, in spots of their bark, in fruit, flowers, and elsewhere; but

especially in the apples of the oak, in the centre of which, surrounded

with a case, a limpid fluid is contained, which, gradually inspissated

and congealed, acquires a most delicate outline, and finally assumes the

form of a maggot; for some time, however, it remains motionless; but by

and by, endowed with motion and sensation it becomes an animal, and

subsequently it breaks forth and takes its flight as a fly.

Aristotle ascribes a similar mode of production to those creatures that

are spontaneously engendered.[187] “Some are engendered of the dew,” he

says, “which falls upon the leaves.” And by and by he adds, “butterflies

are engendered from caterpillars, but these, in their turn, spring from

green leaves, particularly that species of raphanus which is called

cabbage. They are smaller than millet seeds at first, and then they grow

into little worms; next, in the course of three days into caterpillars;

after which they cease from motion, change their shape, and pass into

chrysalides, when they are inclosed in a hard shell; although, if

touched, they will still move. The shell after a long time cracks and

gives way, and the winged animal, which we call a butterfly, emerges.”

But our doctrine--and we shall prove it by and by--is, that all animal

generation is effected in the same way; that all animals, even the most

perfect, are produced from worms; a fact which Aristotle himself seems

to have noted when he says: “In all, nevertheless, even those that lay

perfect eggs, the first conception grows whilst it is yet invisible; and

this, too, is the nature of the worm.”[188] For there is this difference

between the generation of worms and of other animals, that the former

acquire dimensions before they have any definite form or are

distinguished into parts, in conformity with what the philosopher[189]

says in the following sentence: “An animal is fashioned from an entire

worm, not from any one particular part, as in the case of an egg, but

the whole increases and becomes an articulated animal,” i. e. in its

growth it separates into parts.

It is indeed matter worthy of admiration, that the rudiments of all

animals, particularly those possessed of red blood, such as the dog,

horse, deer, ox, common fowl, snake, and even man himself, should so

signally resemble a maggot in figure and consistence, that with the eye

you can perceive no difference between them.

Towards the end of the fifth day or the beginning of the sixth, the head

is divided into three vesicles: the first of these, which is also the

largest, is rounded and black; this is the eye, in the centre of which

the pupil can be distinguished like a crystalline point. Under this

there lies a smaller vesicle, concealed in part, which represents the

brain; and over this lies the third vesicle, like an added crest or

rounded summit crowning the whole, from which the cerebellum is at

length produced. In the whole of these there is nothing to be discovered

but a little perfectly limpid water.

And now the rudiment of the body, which we have called the carina,

distinctly proclaims itself to be the spinal column, to which sides soon

begin to be added, and the wings and the lower extremities present

themselves, projecting slightly from the body of the maggot. The venous

conduits are, further, now clearly referrible to the umbilical vessels.

EXERCISE THE NINETEENTH.

_The fifth inspection of the egg._

On the sixth day the three cells of the head present themselves more

distinctly, and the coats of the eyes are now apparent; the legs and the

wings also bud forth, much in the way in which, towards the end of June,

we see tadpoles getting their extremities, when they quit the water, and

losing their tails assume the form of frogs.

In the chick, the rump has still no other form than is conspicuous in

animals at large, even in serpents; it is a round and slender tail. The

substance of the heart now grows upon the pulsating vesicle; and shortly

afterwards the rudiments of the liver and lungs are distinguished; the

bill, too, makes its appearance at the same time. Everything is of a

pure white colour, especially the bill. About the same epoch all the

viscera and the intestines are conspicuous. But the heart takes

precedence of all the parts; and the lungs are visible before the liver

or brain. The eyes, however, are seen first of all, by reason of their

large size and black colour.

And now, too, the embryo has a power of motion, and raises its head and

slightly twists itself, although there is still nothing of the brain to

be seen, but only a little limpid fluid inclosed in a vesicle. It is at

length a perfect maggot, only differing from a caterpillar in this, that

when worms are set free from their cells they creep about hither and

thither and seek their food, whilst the worm in the egg is stationary,

and, surrounded with its proper food, is furnished with aliment through

the umbilicus.

The viscera and intestines being now formed, and the fœtus able to

execute motions, the anterior portion of the body, without either thorax

or abdomen, is perceived to be completely open; so that the heart

itself, the liver and the intestines, are seen to hang pendulous

externally.

Towards the end of this day and the beginning of the seventh, the toes

are distinguished, and the embryo already presents the outlines of the

chick, and opens its beak, and kicks with its feet; in short, all the

parts are sketched out, but the eyes, above all, are conspicuous. The

viscera, on the contrary, are so indistinct, that Coiter affirms, that

whilst he plainly saw the eyes and beak he could discover no viscus,

even obscurely and confusedly shadowed forth.

The changes that take place from the beginning of the sixth to the end

of the seventh day, occur for the major part in some eggs more quickly,

in others a little more tardily. The coats of the eyes are now visible,

but they only include a colourless and limpid fluid in their interior.

The eyes themselves project somewhat beyond their orbits, and each of

them does not less exceed the brain in size, than the head with which

they are connected exceeds the whole of the rest of the body.

The vesicle, which like a ridge or crest expands beyond the confines of

the brain, occupies the place of the cerebellum; and, like the other

vesicles, is filled with a transparent fluid.

The brain is perceived to be obscurely bipartite, and refracts the light

less than the cerebellum, though it is of a whiter colour. And as the

heart is seen lying without the confines of the thorax, so likewise does

the cerebellum protrude beyond the limits of the head.

If the head be removed, the vessels ascending to the brain may be

observed as bloody points, with the use of a magnifying glass. And now,

too, the rudiments of the spine begin to be first perceived distinct

from the rest of the pulp, of a milky colour, but firmer consistence. So

in the same way, and like flimsy threads of a spider’s web, the ribs and

other bones make their appearance in the guise of milky lines, amidst

the pulp of the body; and the same thing appears more clearly in the

formation of the larger oviparous animals. The heart, lungs, liver, and

by way of intestines certain most delicate filaments, all present

themselves of a white colour. The parenchyma of the liver is developed

upon delicate fibrous stamens over the umbilical vein at the part where

it enters, almost in the same manner as we have said that the rudiments

of the body grow to the vein descending from the heart, or the vesicula

pulsans. For in the same way as grapes grow upon the stalk of the bunch,

buds upon twigs, and the ear upon the straw, does the liver adhere to

the umbilical vein, and arise from it, even as fungi do from trees and

excessive granulations from ulcers, or as sarcoses or morbid growths

spring around the minute branches of conterminous arteries by which they

are nourished, and occasionally attain to an excessive size.

Looking back upon this office of the arteries, or the circulation of the

blood, I have occasionally and against all expectation completely cured

enormous sarcoceles, by the simple means of dividing or tying the little

artery that supplied them, and so preventing all access of nourishment

or spirit to the part affected; by which it came to pass that the

tumour, on the verge of mortification, was afterwards easily extirpated

with the knife, or the searing iron. One man in particular (and this

case I can confirm by the testimony of many respectable persons) had an

enormous hernia carnosa, or sarcocosis of the scrotum, larger than a

human head, and hanging as low as the knee; from its upper part a fleshy

mass, of the thickness of the wrist, or such a rope as is used on

ship-board, extended into the abdomen; and the evil had attained to such

a height, that no one durst attempt the cure, either with the knife or

any other means. Nevertheless, by the procedure above indicated, I

succeeded in completely removing this huge excrescence which distended

the scrotum, and involved the testicle in its middle; this latter organ,

with its vas præparans and vas deferens, and other parts which descend

in the tunica vaginalis, being left all the while safe and uninjured.

But this cure, as well as various others, accomplished in opposition to

vulgar opinion and by unusual procedures, I shall relate at greater

length in my Medical Observations, if God grant me longer life.

I mention such cases with a view of more clearly showing that the liver

grows upon the vessels, and is only developed some time after the

appearance of the blood; that its parenchyma is derived from the

arteries whence the matter is effused, and that for a while it remains

white and bloodless, like various other parts of the body. Now in the

same manner and order precisely as the chick is developed from the egg,

is the generation of man and other animals accomplished.

Whence it appears that the doctrine which makes the liver the author and

fashioner of the blood, is altogether groundless, although both formerly

and at the present time this view obtained universal assent; this was

the reason wherefore the liver was reckoned as among the principal and

first-formed organs of the body. This viscus indeed was so highly

dignified that it was thought to be produced in the very beginning, and

simultaneously with the heart, from the seminal fluid of the mother; and

the medical fable of the three vesicles or three kids, as they were

called, was eagerly defended. Among the number of modern abettors of

such views, Parisanus has of late with confidence enough, but little

skill, been singing to the old measure. These good people do not

consider that the vesicles are in motion in the egg, that the heart is

palpitating and the blood present and perfectly concocted, before any

sign or vestige of the liver appears. The blood is much rather to be

accounted the efficient cause of the liver, than this the author of the

blood: for the liver is engendered after the blood, and from it, being

adnate to the vessels that contain it.

But neither can I agree with the Aristotelians, who maintain that the

heart is the author of the blood; for its parenchyma or proper substance

arises some little time after the blood, and is superadded to the

pulsating vesicles. I am, however, in much doubt as to whether the

pulsating vesicle or point, or the blood itself be the older; whether it

be the fluid contained, or the containing sacs. It is obvious,

nevertheless, that that which contains is formed for the sake of that

which is contained, and is, therefore, made later. And this much, upon

the faithful testimony of our eyes, is certain, that the first particle

and prime basis of the body are the veins, to which all the other parts

are posthumous and superadded. But upon this point we shall say more by

and by.

Meantime we may be permitted to smile at that factitious division of the

parts into spermatic and sanguineous; as if any part were produced

immediately from the seminal fluid, and all did not spring from the same

source!

I return to our subject. The colliquament now extends over more than

half the egg. The heart, hanging outwards, is at some short distance

from the body. And if you look attentively you may perceive some of the

umbilical vessels pulsating.

EXERCISE THE TWENTIETH.

_The sixth inspection._

Everything is still more distinct upon the seventh day, and the

rudiments of several of the particular parts are now conspicuous, viz.,

the wings, legs, genital organs, divisions for the toes, thighs, ilia,

&c. The embryo now moves and kicks, and the form of the perfect chick is

recognizable; from this time forward, indeed, nothing is superadded; the

very delicate parts only increase in size. The more the parts grow the

more is the albumen consumed, and the external membranes united come to

be of the nature of the secundines, and ever more and more closely

represent the umbilical cord. Wherefore I conceive that, from the

seventh, we may at once pass on to the tenth day, nothing of any moment

occurring in this interval which is not particularly noted by other

writers, especially by Aristotle.

It happens, nevertheless, that when a number of eggs are examined

together, some are found more precocious and forward, having everything

more distinct; others, again, are more sluggish, and these have the

parts less apparent. The season of the year, the place where the

incubation is carried on, the sedulousness with which it is performed,

and other accidents, have undoubtedly great influence on this diversity

of result. I remember on one occasion, on the seventh day to have seen

the cavity in the blunt end enlarged in a sluggish egg, the colliquament

covered with veins, the vermicular embryo in its middle, the rudiments

of the eyes, and all the rest as it is met with in the generality of

eggs on the fifth day; but the pulsatory vesicles were not yet apparent,

nor was the trunk or root of the veins from which we have said that they

originate, yet to be discovered. I therefore regarded this egg as of a

feeble nature and left behind, as possessed of an inadequate

reproductive faculty, and near to its death; all the more when I

observed its colliquament less pellucid and refractive than usual, and

the vessels not of such a bright red colour as wont. When the vital

spirit is about to escape, that part which is first influenced in

generation and earliest attracts attention is also the first that fails

and disappears.

EXERCISE THE TWENTY-FIRST.

_The inspection after the tenth day._

All that presents itself on the tenth day is so accurately described by

Aristotle that scarcely anything remains for us to add. Now his opinion,

according to my interpretation of it, is this, viz., that “on the tenth

day the entire chick is conspicuous,”[190] being pellucid and white in

every part except the eyes and the venous ramifications. “The head at

this time is larger than the whole of the rest of the body; and eyes

larger than the head are connected with it,” (adhering, and being in

some sort appended to the head,) “but having as yet no pupils,”

(perfectly formed pupils must here be understood, for it is not

difficult to make out the distinct tunics of the eye at this epoch;)

“the eyes, if removed at this time, will be found as large as beans and

black, and if they be incised, a clear humour flows out, cold, and

refracting the light powerfully, but nothing else,” i. e., in the whole

head there is nothing but the limpid water which has been mentioned.

Such is the state of matters from the seventh to the tenth day, as we

have said above. “At the same time,” he continues, “the viscera also

appear, and all that appertains to the abdomen and intestines,” viz.,

the substance of the heart, the lungs, liver, &c., all of a white

colour, mucilaginous, pulpy, without any kind of consistency. “The

veins, too, that issue from the heart are already in connexion with the

umbilicus, from which one vein extends to the membrane that includes the

vitellus, which has now become more liquid and diffluent than it was

originally; another to the membrane which surrounds everything,” (i. e.,

the tunica colliquamenti,) “and embraces the fœtus, the vitellus and the

interjacent fluid. For the embryo increasing somewhat, one portion of

the vitellus is superior, another inferior; but the albumen in the

middle is liquid, and still extends under the inferior portion of the

vitellus, as it did previously.” Thus far Aristotle.

And now the arteries are seen distinctly accompanying the veins, both

those that proceed to the albumen and those that are distributed to the

vitellus. The vitellus also at this time liquefies still more and

becomes more diffluent, not entirely, indeed, but, as already said, that

portion of it which is uppermost; neither do the branches of the veins

proceed to every part of the vitellus alike, but only to that part which

we have spoken of as resembling melted wax. The veins that are

distributed to the albumen have, in like manner, arteries accompanying

them. The larger portion of the albumen now dissolves into a clear

fluid, the colliquament, which surrounds the embryo that swims in its

middle, and comes between the two portions of the vitellus, viz., the

superior and the inferior; underneath all (in the sharp end of the egg),

the thicker and more viscid portion of the albumen is contained. The

superior portion of the yelk already appears more liquid and diffluent

than the inferior; and wherever the branches of the veins extend, there

the matter seems suddenly to swell and become more diffluent.

“On the tenth day,” continues our author, “the albumen subsides, having

now become a small tenacious, viscid, and yellowish mass”--so much of

it, that is to say, as has not passed into the state of colliquament.

For already the larger portion of the white has become dissolved, and

has even passed into the body of the embryo, viz., the whole of the

thinner albumen, and the greater portion of the thicker. The yelk, on

the contrary, rather looks larger than it did in the beginning. Whence

it clearly appears that the yelk has not as yet served for the nutrition

of the embryo, but is reserved to perform this office by and by. In so

far as we can conjecture from the course and distribution of the veins,

the embryo from the commencement is nourished by the colliquament; upon

this blood-vessels are first distributed, and then they spread over the

membrane of the thinner albumen, next over the thicker albumen, and

finally over the vitellus. The thicker albumen serves for nutriment

after the thinner; the vitellus is drawn upon last of all.

The delicate embryo, consequently, whilst it is yet in the vermicular

state, is nourished with the thinnest and best concocted aliment, the

colliquament and thinner albumen; but when it is older it has food

supplied to it more in harmony with its age and strength.

Aristotle describes the relative situation of the several parts in the

following words: “In the anterior and posterior part, the membrane of

the egg lies under the shell,--I do not mean the membrane of the shell

itself, but one under this, in which there is contained a clear

fluid”--the colliquament; “then the chick and the membrane including it,

which keeps it distinct from the fluid around it.” But here I suspect

that there is an error in the text; for as the author himself indicates

the thing, it ought rather to stand thus: “then the chick, enveloped in

a membrane, continues or swims in the clear fluid;” which membrane is

not exterior to the one that immediately lines the shell, but another

lying under this; which, when the first or external albumen is consumed,

and the remainder of the thicker albumen is depressed into the sharp end

of the egg, of two membranes forms a single tunic that now begins to

present itself like the secundine called the chorion. And Aristotle says

well, “there is a clear fluid contained in it,” by which words he does

not mean the albumen, but the colliquament derived from the albumen, and

in which the embryo swims; for the albumen that remains subsides into

the small end of the egg.

EXERCISE THE TWENTY-SECOND.

_The inspection after the fourteenth day._

From the seventh to the fourteenth day everything has grown and become

more conspicuous. The heart and all the other viscera have now become

concealed within the abdomen of the embryo, and the parts that formerly

were seen naked and projecting externally, can now only be perceived

when the thorax and abdomen are laid open. The chick too now begins to

be covered with feathers, the roots of which are first perceived as

black points. The pupils of the eyes are distinguished; the eyelids

appear, as does also the membrana nictitans in the greater canthus of

the eye, a membrane which is proper to birds, and which they use for

cleansing the eyeball. The convolutions of the brain farther make their

appearance; the cerebellum is included within the skull; and the tail

acquires the characteristic shape of the bird’s rump.

After the fourteenth day the viscera, which up to this time have been

white, gradually begin to assume a flesh or reddish colour. The heart,

having now entered the penetralia of the thorax and been covered with

the sternum, inhabits the dwelling place which itself had formed. The

cerebrum and cerebellum acquire solidity under the dome of the skull;

the stomach and intestines, however, are not yet included within the

abdomen, but, connected with the parts within, hang pendulous

externally.

Of the two vessels that proceed from the abdomen to the umbilicus, near

the anus, one is an artery, as its pulse proclaims, and arises from the

arteria magna or aorta, the other is a vein, and extends from the

vitellus by the side of the intestines to the vena portæ, situated in

the concave part of the liver. The other trunk of the umbilical vessels,

collecting its branches from the albumen, passes the convexity of the

liver, and enters the vena cava near the base of the heart.

As all these things go on becoming clearer from day to day, so the

greater portion of the albumen is also gradually consumed; this,

however, is nowise the case with the vitellus, which remains almost

entire up to this time, and indeed is seen of the same size as it was

the first day.

In the course of the following days five umbilical vessels are

conspicuous; one of these is the great vein, arising from the cava above

the liver, and distributing its branches to the albumen; two other veins

proceed from the porta, both having the same origin, and run to the two

portions of the vitellus, which we have but just described; and these

are accompanied by two arteries arising one on either side from the

lumbars.

The chick now occupies a larger space in the egg than all the rest of

the matter included in it, and begins to be covered with feathers; the

larger the embryo grows, the smaller is the quantity of albumen that is

present. It is also worthy of observation, that the membrane of the

colliquament which we have said unites with the external investing

membrane, and constitutes the secundine or chorion, now includes the

whole of the vitellus in one, and becoming contracted, draws the

vitellus along with the intestines towards the chick, conjoins them with

its body, and incloses them as it were in a thick sac. Everything that

was previously extremely delicate and transparent, becomes more opaque

and fleshy as the sac contracts, which at length, like a hernial tumour

of the scrotum, includes and supports both the intestines and the yelk;

contracting every day in a greater and greater degree, it comes finally

to constitute the abdomen of the chick. You will find the yelk, about

the eighteenth day, lying [in its bag] among the intestines, the belly

at large being lax; yet are the parts not so firmly fixed but that the

intestines (as in the case of a scrotal hernia), along with the

vitellus, can be pushed up into the belly, or forced out of it as it

were into a pouch. I have occasionally seen the vitellus prolapsed in

this way from the abdominal cavity of a pigeon, which had been

prematurely excluded from the shell in the summer season.

The chick at this epoch looks big-bellied and as if it were affected

with a hernia, as I have said. And now the colliquament, which was at

first in large quantity, gradually grows turbid, suffers change, and is

consumed, so that the chick comes to lie bent over the vitellus. At the

same period, before the liver assumes its sanguineous colour, and

performs the business of what is called the second concoction, the bile,

which is commonly believed to be separated as an excretion by the power

of the liver, is seen of a green colour between the lobes of that organ.

In the cavity of the stomach there is a limpid fluid contained,

obviously of the same appearance and taste as the colliquament in which

the fœtus swims; this passing on by the intestines, gradually changes

its colour, and is converted into chyle; and finally in the lower

portion of the bowels an excrementitious matter is encountered, of the

same character as that which is met with in the lower intestines of

chicks already excluded from the egg. When the chick is further advanced

you may even see this fluid concocted and coagulated; just as in those

animals that feed on milk, a coagulum is formed, which afterwards

separates into serum and firmer curd.

When the albumen is almost all removed, and only a very small quantity

of the colliquament is left, for several days before the exclusion, the

chick no longer swims, but, as I have said, bends over the vitellus; and

rolled up into a round ball, with the head for the most part placed

between the right thigh and wing, it is seen with its beak, nails,

feathers, and all other parts complete. Sometimes it sleeps, and

sometimes it wakes, and moving about it breathes and chirps. If you

apply the egg to your ear, you will hear the chick within making a

noise, kicking, and unquestionably chirping; according to Aristotle, he

now also uses his eyes. If you cautiously drop the egg into warm water,

it will swim, and the chick within, aroused by the warmth, will leap,

and, as I have already said, cause the egg to tumble about. And it is by

this means that our country folks distinguish prolific from unproductive

eggs which sink when put into water.

When the albumen is entirely gone, just before the exclusion, the

umbilical vessel, which we have described as distributed to the albumen,

is obliterated; or as Aristotle says,[191] “that umbilicus which

proceeds to the external secundines is detached from the animal and

dies; but the one which leads to the vitellus becomes connected with the

small intestine of the chick.”

The excrement that is first formed in the intestines is white and

turbid, like softened egg-shell; and some of the same matter may be

found contained in the secundines. The philosopher admits this when he

says: “At the same time, too, the chick discharges a large quantity of

excrement into the outer membrane; and there are white excrements within

the abdomen, as well as those that have been evacuated.”

Time running on, very shortly before the exclusion, light green fæces

are formed, similar to those which the chick discharges when excluded

from the egg. In the crop, too, we can discover a portion of the

colliquament which has been swallowed; and in the stomach some curd or

coagulum.

Up to this time the liver has not yet acquired its purple or blood-red

colour, but has a tint verging from white into yellow, such as the liver

of fishes presents. The lungs, however, are of a florid red.

The yelk is now contained in the abdomen among the intestines: and this

is the case not merely whilst the chick is in the egg, but even after

its exclusion, and when it is running about following its mother in

search of food. So that what Aristotle frequently asserts appears to be

absolutely true, viz., that the yelk is destined for the food of the

chick; and the chick does certainly use it for food, included in his

interior as it is, during the few first days after his exclusion, and

until such time as his bill gains the hardness requisite to break and

prepare his food, and his stomach the strength necessary to digest it.

And, indeed, the yelk of the egg is very analogous to milk. Aristotle

gives us his support in this opinion in the place already so frequently

referred to:[192] “The chick now lies over much of the yellow, which at

last diminishes, and, in process of time, disappears entirely, being all

taken into the body of the bird, where it is stored, so that on the

tenth day after the exclusion of the chick, if the belly be laid open,

you will still find a little of the yelk upon the intestines.” I have

myself found certain remains of the yelk even upon the thirteenth day;

and if the argument derivable from the duct of the umbilical veins which

we have described as terminating in the porta of the liver by one or

another trunk, be of any avail, the chick is already nourished almost in

the same manner as it is subsequently, the sustenance being attracted

from the yelk by the umbilical vessels, in the same way as chyle is by

and by transmitted by the mesenteric veins from the intestines. For the

vessels terminate in either case in the porta of the liver, to which the

nourishment attracted in the same way is in like manner transmitted. It

is not necessary, therefore, to have recourse to any lacteal vessels of

the mesentery, which, in the feathered tribes, are nowhere to be

distinguished.

Let me be permitted here to add what I have frequently found: With a

view to discovering more distinctly the relative situations of the

embryo and the fluids, I have boiled an egg hard, from the fourteenth

day of the incubation up to the day when the exclusion would have taken

place, the major part of the albumen being already consumed, and the

vitellus divided. Breaking the shell, and regarding the position of the

chick, I found both the remains of the albumen and the two portions of

the vitellus (which we have said are divided by the colliquation induced

by the gentle heat), possessing the consistency, colour, taste, and

other qualities which distinguish the yelks of unincubated eggs

similarly boiled. I have, therefore, frequently asked myself how it came

to pass that unprolific eggs set under a hen are made to putrefy and

become offensive by the same extraneous heat which produces no such

effect upon prolific eggs, both of the fluids of which remain sweet and

unchanged, although they have an embryo in the midst of them, (and this

even containing some small quantity of excrementitious matter within

it,) so that did any one eat the yelk of such an egg in the dark, he

would not distinguish it from that of a fresh egg which had never been

sat upon.

EXERCISE THE TWENTY-THIRD.

_Of the exclusion of the chick, or the birth from the egg._

The egg is, as we have said, a kind of exposed uterus, and place in

which the embryo is fashioned: for it performs the office of the uterus

and enfolds the chick until the due time of its exclusion arrives, when

the creature is born perfect. Oviparous animals consequently are not

distinguished from viviparous by the circumstance of the one bringing

forth their young alive, and the other not doing so; for the chick not

only lives and moves within the egg, but even breathes and chirps whilst

there; and, when it escapes from the shell, enjoys a more perfect

existence than the fœtus of animals in general. Oviparous and viviparous

animals rather differ in their modes of bringing forth; the uterus or

place in which the embryo is formed being within the animal in

viviparous tribes, where it is cherished and brought to maturity, whilst

in oviparous tribes the uterus, or egg, is exposed or without the

animal, which, nevertheless, by sitting on it does not cherish it less

truly than if it were still contained within the body.

For though the mother occasionally quits her eggs on various errands, it

is only for a short season; she still has such affection for them that

she speedily returns, covers them over, cherishes them beneath her

breast and carefully defends them; and this on to the twenty-first or

twenty-second day, when the chicks, in search of freer air, break the

shell and emerge into the light.

Now we must not overlook a mistake of Fabricius, and almost every one

else in regard to this exclusion or birth of the chick. Let us hear

Fabricius.[193]

“The chick wants air sooner than food, for it has still some store of

nourishment within it; in which case the chick, by his chirping, gives a

sign to his mother of the necessity of breaking the shell, which he

himself cannot accomplish by reason of the hardness of the shell and the

softness of his beak, to say nothing of the distance of the shell from

the beak, and of the position of the head under the wing. The chick,

nevertheless, is already so strong, and the cavity in the egg is so

ample, and the air contained within it so abundant, that the breathing

becomes free and the creature can emit the sounds that are proper to it;

these can be readily heard by a bystander, and were recognized both by

Pliny and Aristotle,[194] and perchance have something of the nature of

a petition in their tone. For the hen hearing the chirping of the chick

within, and knowing thereby the necessity of now breaking the shell in

order that the chick may enjoy the air which has become needful to it,

or if you will, you may say, that desiring to see her dear offspring,

she breaks the shell with her beak, which is not hard to do, for the

part over the hollow, long deprived of moisture, and exposed to the heat

of incubation, has become dry and brittle. The chirping of the chick is

consequently the first and principal indication of the creature desiring

to make its escape, and of its requiring air. This the hen perceives so

nicely, that if she hears the chirping to be low and internal, she

straightway turns the egg over with her feet, that she may break the

shell at the place whence the voice proceeds without detriment to the

chick. Hippocrates adds,[195] “Another indication or reason of the

chick’s desiring to escape from the shell, is that when it wants food it

moves vigorously, in search of a larger supply, by which the membrane

around it is torn, and the mother breaking the shell at the place where

she hears the chick moving most lustily, permits it to escape.”

All this is stated pleasantly and well by Fabricius; but there is

nothing of solid reason in the tale. For I have found by experience that

it is the chick himself and not the hen that breaks open the shell, and

this fact is every way in conformity with reason. For how else should

the eggs that are hatched in dunghills and ovens, as in Egypt and other

countries, be broken in due season, where there is no mother present to

attend to the voice of the supplicating chick, and to bring assistance

to the petitioner? And how again are the eggs of sea and land tortoises,

of fishes, silkworms, serpents, and even ostriches to be chipped? The

embryos in these have either no voice with which they can notify their

desire for deliverance, or the eggs are buried in the sand or slime

where no chirping or noise could be heard. The chick therefore is born

spontaneously, and makes its escape from the eggshell through its own

efforts. That this is the case appears from unquestionable arguments:

when the shell is first chipped, the opening is much smaller than

accords with the beak of the mother; but it corresponds exactly to the

size of the bill of the chick, and you may always see the shell chipped

at the same distance from the extremity of the egg, and the broken

pieces, especially those that yield to the first blows, projecting

regularly outwards in the form of a circlet. But as any one on looking

at a broken pane of glass can readily determine whether the force came

from without or from within, by the direction of the fragments that

still adhere, so in the chipped egg it is easy to perceive, by the

projection of the pieces around the entire circlet, that the breaking

force comes from within. And I myself and many others with me besides,

hearing the chick scraping against the shell with its feet, have

actually seen it perforate this part with its beak, and extend the

fracture in a circle like a coronet. I have further seen the chick

raise up the top of the shell upon its head and remove it.

We have gone at length into some of these matters, as thinking that they

were not without all speculative interest, as we shall show by and by.

The arguments of Fabricius are easily answered. For I admit that the

chick in ovo produces sounds, and these perchance may even have

something of the implorative in their nature; but it does not therefore

follow that the shell is broken by the mother. Neither is the bill of

the chick so soft, nor yet so far from the shell, that it cannot pierce

through its prison walls, particularly when we see that the shell, for

the reasons assigned, is extremely brittle. Neither does the chick

always keep its head under its wing, so as to be thereby prevented from

breaking the shell, but only when it sleeps or has died. For the

creature wakes at intervals and scrapes and kicks, and struggles,

pressing against the shell, tearing the investing membranes, and chirps,

(and that this is done whilst petitioning for assistance I willingly

concede,) all of which things may readily be heard by any one who will

use his ears. And the hen listening attentively when she hears the

chirping deep within the egg does not break the shell, but she turns the

egg with her feet and gives the chick within another and a more

commodious position. But there is no occasion to suppose that the chick

by his chirping informs his mother of the propriety of breaking the

shell, or seeks deliverance from it. For very frequently for two days

before the exclusion you may hear the chick chirping within the shell.

Neither is the mother, when she turns the egg, looking for the proper

place to break it; but as the child when uncomfortably laid in his

cradle is restless and whimpers and cries, and his fond mother turns him

this way and that, and rocks him till he is composed again, so does the

hen when she hears the chick restless and chirping within the egg, and

feels it, when hatched, moving uneasily about in the nest, immediately

raise herself and observe that she is not pressing on it with her

weight, or keeping it too warm, or the like, and then with her bill and

her feet she moves and turns the egg until the chick within is again at

its ease and quiet.

EXERCISE THE TWENTY-FOURTH.

_Of twin-bearing eggs._

Twin-bearing eggs are such as produce twin chickens, and according to

Aristotle,[196] “are possessed of two yelks, which, in some are

separated by a layer of thin albumen, that they may less encroach on one

another; in others, however, there is nothing of the sort, and then the

two yelks are in contact.”

I have frequently seen twin eggs, each of the yelks in which was

surrounded by an albumen, with common and proper membranes surrounding

them. I have also met with eggs having two yelks connate, as it were,

both of which were embraced by a single and common albumen.

“Some fowls” says Aristotle,[197] “always produce twins, in which the

particulars relating to the yelk that have been stated are clearly

perceived. A certain fowl laid within two of twenty eggs, all of which,

except those that were unprolific, produced twins. Of the twins,

however, one was always larger, the other smaller, and the smaller chick

was frequently deformed in addition.”

With us twin eggs are occasionally produced, and twin chicks too,

although very rarely, are engendered. I have never myself, however, seen

both of these chicks live and thrive; one of them either died within the

egg or at the time of the exclusion. And this the words of Aristotle

prepare us to expect, when he says “one of the two is larger, the other

smaller;” this is as much as to say that one of them is stronger and of

greater age, the other weaker and less prepared for quitting the shell:

my own opinion therefore is, that the two yelks are of different origins

and maturity. It is therefore scarcely possible but that the stronger

and more advanced chick, if the egg be broken and it emerge into the

light, will cause the blight and abortion of the other. But if the

stronger bird do not chip the shell, he himself is threatened with a

present danger, viz. want of air. At the exclusion from the shell,

consequently, certain death hangs over one or other, if not over both.

Fabricius either not observing the above words of Aristotle, or

neglecting them, says: “If an egg have now and then two yelks, it

engenders a chick having four legs or wings, and two heads--a monster,

in short; never two chicks distinct from one another, and that can be

spoken of as a pair; there is but one trunk, to which are appended two

heads, &c.”

Whence we may infer that he himself had never seen nor heard from

credible persons that such eggs produce two pullets, and therefore that

he agrees with me in regarding such eggs as rare, and in holding that

they never produce two chicks both alike capable of living.

I am surprised nevertheless that, with the authority of Aristotle before

him, he should have said that “two chicks, distinct and separate, are

_never_ produced from such eggs,” but always a monster; the rather as he

thinks that the embryo is engendered from the chalazæ as from the

appropriate matter, and he could not but see that there are four chalazæ

in every twin-egg.

I should rather imagine that when two vitelli are included by the same

albumen in a twin-egg, and are so intimately associated that their

cicatriculæ, when they are resolved together, constitute a single eye or

colliquament, may engender a monstrous embryo with four feet, two heads,

&c., because I see nothing to hinder this; and such a production do I

conceive to have been engendered by the egg of which Fabricius speaks.

But where two yelks have existed separately, parted by their several

membranes, and furnished with chalazæ, albumens, and all else requisite

to the generation of the chick, I hold that we must conclude, with

Aristotle, that such an egg, as it has all the parts of two eggs except

the shell, so does it also possess the faculty or faculties of as many;

and unless it be a wind or barren egg, that it will for the most part

produce two embryos, and but rarely a single monstrous individual.

EXERCISE THE TWENTY-FIFTH.

_Certain Deductions from the preceding History of the Egg._

Such is the history of the hen’s egg; in which we have spoken of its

production, and of its action or faculty to engender a chick, at too

great length, it may appear to those who do not see the end and object

of such painstaking, of such careful observation. Wherefore I think it

advisable here to state what fruits may follow our industry, and in the

words of the learned Lord Verulam, to “enter upon our second vintage.”

Certain theorems, therefore, will have to be gathered from the history

given; some of which will be quite certain, some questionable and

requiring further sifting, and some paradoxical and opposed to popular

persuasion. Some of these, moreover, will have reference to the male,

some to the female, several to the egg, and finally, a few to the

formation of the chick. When these have been carefully discussed

seriatim, we shall be in a condition to judge with greater certainty and

facility of the generation of all other animals.

EXERCISE THE TWENTY-SIXTH.

_Of the nature of the egg._

Of the theorems that refer to the egg, some teach us what it is, some

show its mode of formation, and others tell of the parts which compose

it.

It is certain, in the first place, that one egg produces one chick only.

Although the egg be in a certain sense an external uterus, still it most

rarely engenders several embryos, but by far the most frequently

produces no more than a single pullet. And when an egg produces two

chicks, which it does sometimes, still is this egg to be reputed not

single but double, and as possessed of the nature and parts of two eggs.

For an egg is to be viewed as a conception proceeding from the male and

the female, equally endued with the virtue of either, and constituting

an unity from which a single animal is engendered.

Nor is it the beginning only, but the fruit and conclusion likewise. It

is the beginning as regards the being to be engendered; the fruit in

respect of the two parents: at once the end proposed in their

engendering, and the origin of the chick that is to be. “But the seed

and the fruit,” according to Aristotle,[198] “differ from one another in

the relations of prior and posterior; for the fruit is that which comes

of another, the seed is that from which this other comes: were it

otherwise, both would be the same.”

The egg also seems to be a certain mean; not merely in so far as it is

beginning and end, but as it is the common work of the two sexes and is

compounded by both; containing within itself the matter and the plastic

power, it has the virtue of both, by which it produces a fœtus that

resembles the one as well as the other. It is farther a mean between the

animate and the inanimate world; for neither is it wholly endowed with

life, nor is it entirely without vitality. It is still farther the

mid-passage or transition stage between parents and offspring, between

those who are, or were, and those who are about to be; it is the hinge

and pivot upon which the whole generation of the bird revolves. The egg

is the terminus from which all fowls, male and female, have sprung, and

to which all their lives tend,--it is the result which nature has

proposed to herself in their being. And thus it comes that individuals

in procreating their like for the sake of their species, endure for

ever. The egg, I say, is a period or portion of this eternity; for it

were hard to say whether an egg exists for the sake of the chick that it

engenders, or the pullet exists for the sake of the egg which it is to

engender. Which of these was the prior, whether with reference to time

or nature,--the egg or the pullet? This question, when we come to speak

of the generation of animals in general, we shall discuss at length.

The egg, moreover,--and this is especially to be noted,--corresponds in

its proportions with the seeds of plants, and has all the same

conditions as these, so that it is to be regarded, not without reason,

as the seed or sperma of the common fowl, in the same way as the seeds

of plants are justly entitled their eggs, not only as being the _matter_

or that from which, but the _efficient_ or that by which the pullet is

engendered. In which finally no part of the future offspring exists _de

facto_, but in which all parts inhere _in potentia_.

The seed, properly so called, differs however from the _geniture_, which

by Aristotle is defined to be “that which, proceeding from the

generator, is the cause, that which first obtains the principle of

generation; in those, to wit, whom nature destined to copulate. But the

seed is that which proceeds from these two in their connection: and such

is the seed of all vegetables, and of some animals, in which the sexes

are not distinct; like that which is first produced by male and female

commingled, a kind of promiscuous conception, or animal; for this

already possesses what is required of both.”

The egg consequently is a natural body endowed with animal virtues, viz.

principles of motion and rest, of transmutation and conservation; it is,

moreover, a body which, under favorable circumstances, has the capacity

to pass into an animal form; heavy bodies indeed do not sink more

naturally, nor light ones float, when they are unimpeded, than do seeds

and eggs in virtue of their inherent capacity become changed into

vegetables and animals. So that the seed and the egg are alike the fruit

and final result of the things of which they are the beginning and

efficient cause.

For a single pullet there is a single egg; and so Aristotle[199] says:

“from one seed one body is engendered; for example, from a single grain

of wheat one plant; from a single egg one animal; for a twin-egg is, in

fact, two eggs.”

And Fabricius[200] with truth observes: “The egg is not only an exposed

uterus, and place of generation, but that also on which the whole

reproduction of the pullet depends, and which the egg achieves as agent,

as matter, as instrument, as seat, and all else, if more there be, that

is needful to generation.” He shows it to be an organ because it

consists of several parts, and this, from the statement of Galen, who

will have the very essence of an organ to be that “it consist of several

parts, all of which conspire to one and the same action though diverse

in faculty and use; for some are principal instruments in the action;

some are indispensable to it,--without them it could not take place;

some secure its better performance; and some, in fine, are extant for

the safety and preservation of everything else.” He also shows it to be

an _agent_, when from Aristotle and Galen he lays down the two actions

of the egg, viz.: “the generation of the chick, and the growth and

nutrition of the pullet.” At the conclusion he expresses himself clearly

in these words: “In the works of nature we see conjunct and one, the

artificer, the instrument, and the matter; the liver, for instance, is

both the agent and the instrument for the production of the blood; and

so every part of the body; Aristotle,[201] therefore, said well that the

moving powers were not easily distinguished from the instruments. In

artificial things, indeed, the artificer and the instrument are

distinct, as much so as the workman and his hammer, the painter and his

pencil. And the reason adduced by Galen[202] is this: that in things

made by art the artificer is without the work; in natural things, again,

the artificer is within it, conjunct with the instruments, and pervading

the whole organization.”

To this I add these perspicuous words of Aristotle.[203] “Of extant

things some are consistent with nature, others with other causes.

Animals and their parts, and plants, and simple bodies, as earth, fire,

air, and water, consist with nature, and are allowed universally to do

so; but these bodies differ entirely from those that do not consist with

nature. For whatsoever consists with nature is seen to have within

itself a principle of motion and of rest, now according to place, now

according to increment and decrement, and again according to change. A

couch or litter, a garment, and other things of the same description,

however designated, inasmuch as they are made by art, have no inherent

faculty of change; but inasmuch as they are made of [wood, or] earth, or

stone, [or of wool, silk, or linen,] or of mixtures of these, they have

such a faculty. As if nature were a certain principle and cause

wherefore that should move and be at rest in which she inheres

originally, independently, and not by accident. I say, particularly,

_not by accident_, because it might happen that one being a physician

should himself be the cause of his own good health; but he is not

familiar with medicine in the same respect as he has worked his own

cure; it happens simply that the man who here recovers his health is a

physician. It therefore occasionally happens, that these two things are

distinct and separate. But it is not otherwise with everything besides

that is of art: none of these has in itself a principle of performance

or action, though some of them have such a principle in other things and

beyond themselves, such as a house, and aught else that is made with

hands; and some have even such a principle inherent, but not _per se_

and independently: everything, for example, may by accident become a

cause to itself. Nature is therefore, as stated [that which has an

inherent principle of motion]; and those things have nature within them

which possess this principle. Now all such are substances; for nature is

always some subject, and inheres in the subject.”

These things I have spoken of at length, and even quoted the words of

the writers appealed to, that it might thence appear first, that all I

attribute to the egg is actually there, viz.: matter, organ, efficient

cause, place, and everything else requisite to the generation of the

chick; and next and more especially, that the truth in regard to the

following very difficult questions might be made clearly to appear,

viz.: Which and what principle is it whence motion and generation

proceed? By what virtue does the semen act, according to Aristotle? What

is it that renders the semen itself fruitful? (for the philosopher will

have it that nature in all natural bodies is the innate principle of

motion and of rest, and not any second accident.) Whether is that which

in the egg is cause, artificer, and principle of generation and of all

the vital and vegetative operations--conservation, nutrition,

growth--innate or superadded? and whether does it inhere primarily, of

itself, and as a kind of nature, or intervene by accident, as the

physician in curing diseases? Whether is that which transforms the egg

into a pullet inherent or acquired, or is it already conceived in the

ovary, and does it nourish, augment, and perfect the egg there?

What is it besides that preserves the egg sweet after it is laid? What

is it that renders an egg fruitful--is it to be called soul, or a

portion of the soul, or something belonging to the soul, or something

having a soul, or is it intelligence, or, finally, is it Divinity?

seeing that it acts to a definite end, and orders all with inimitable

providence and art, and yet in an incomprehensible manner, always

obtaining what is best both for simple being and for well-being, for

protection also and for ornament. And all this not only in the fruitful

egg which it fecundates, but in the hypenemic egg which it nourishes,

causes to increase, and preserves. Nay, it is not merely the vitellus in

the vitellarium or egg-bed, but the smallest speck whence the yelk is

produced, of no greater size than a millet or a mustard-seed, that it

nourishes and makes to grow, and finally envelopes with albumen, and

furnishes with chalazæ, and surrounds with membranes and a shell. For it

is probable that even the barren egg, whilst it is included within the

fowl and is connected with her, is nourished and preserved by its

internal and inherent principle, and made to increase (not otherwise

than the eggs of fishes and frogs, exposed externally, increase and are

perfected), and to be transformed from a small speck into a yelk, and

transferred from the ovary to the uterus (though it have no connexion

with the uterus), there to be endued with albumen, and at length to be

completed with its chalazæ, membranes, and shell.

But what that may be in the hypenemic egg as well as in the fruitful

one, which in a similar manner and from the same causes or principles

produces the same effects; whether it be the same soul, or the same part

of the soul, or something else inherent in both, must be worthy of

inquiry: it seems probable, however, that the same things should proceed

from similar causes.

Although the egg whilst it is being produced is contained within the

fowl, and is connected with the ovary of the mother by a pedicle, and is

nourished by blood-vessels, it is not therefore to be spoken of as a

part of the mother; nor is it to be held as living and vegetating

through her vital principle, but by a virtue peculiar to itself and an

internal principle; just as fungi, and mosses, and the misletoe, which

although they adhere to vegetables and are nourished by the same sap as

their leaves and germs, still form no part of these vegetables, nor are

they ever so esteemed. Aristotle, with a view to meeting these

difficulties, concedes a vegetative soul to the egg, even to the

hypenemic one. He says:[204] “Females, too, and all things that live are

endowed with the vegetative virtue of the soul, as has been often said;

and therefore this [hypenemic] egg is perfect as the conception of a

plant, but imperfect as that of an animal.” And he inculcates the same

doctrine elsewhere,[205] when he asks: “In what manner or sense are

hypenemic eggs said to live? For they cannot do so in the same sense as

fruitful eggs, otherwise a living thing might be engendered by their

agency. Nor do they comport themselves like wood or stone; because these

perish by a kind of corruption, as having formerly had life in a certain

manner. It is positive, therefore, that hypenemic eggs have a certain

kind of soul potentially; but what? of necessity that ultimate soul,

which is the appanage of vegetables; for this equally inheres in all

things, in animals as well as vegetables.”

But it is not the same soul that is found in hypenemic as in fruitful

eggs; otherwise would a pullet be indifferently produced from both; but

how and in what respects the soul attached to each is different from the

other, Aristotle does not sufficiently explain, when he inquires:[206]

“Wherefore are all the parts of an egg present in the hypenemic egg, and

it still incapable of producing a chick? because,” he replies, “it is

requisite that it have a sensitive soul.” As if in fruitful eggs,

besides the vegetative soul, there were a sensitive soul present. Unless

you understand the vegetative soul as inhering _actually_ in the

fruitful egg, which contains the sensitive soul within it _potentially_;

whence the animal, and the sensible parts of the animal are subsequently

produced. But neither do writers satisfactorily untie this knot, nor set

the mind of the inquirer free from the difficulties that entangle him.

For he sees that the egg is a true animal seed, according to this

sentence of the Stagyrite:[207] “In those things endowed with life, in

which the male and female sexes are not distinct, the seed is already

present as a conception. I entitle _conception_ the first mixture from

the male and female (the analogue of the vegetable seed therefore).

Wherefore from one seed there is engendered one body, as from one egg

one animal.”

It appears, consequently, that for one egg there is one soul or vital

principle.[208] But whether is this that of the mother, or that of the

father, or a mixture of the two? And here the greatest difficulties are

occasioned by those eggs that are produced by the concurrence of animals

of different species, as, for example, of the common fowl and pheasant.

In such an egg, I ask, is it the vital principle of the father or that

of the mother, which inheres? or is it a mixture of the two? But how can

vital principles be mingled, if the vital principle (as form) be act and

substance, which it is, according to Aristotle? For no one will deny,

whatever it be ultimately which in the fruitful egg is the beginning and

cause of the effects we witness, that it is a substance susceptible of

divers powers, forces, or faculties, and even conditions,--virtues,

vices, health and sickness. For some eggs are esteemed to be longer,

others shorter lived; some engender chickens endowed with the qualities

and health of body that distinguished their parents, others produce

young that are predisposed to disease. Nor is it to be said that this is

from any fault of the mother, seeing that the diseases of the father or

male parent are transferred to the progeny, although he contributes

nothing to the matter of the egg; the procreative or plastic force which

renders the egg fruitful alone proceeding from the male; none of its

parts being contributed by him. For the semen which is emitted by the

male during intercourse does by no means enter the uterus of the female,

in which the egg is perfected; nor can it, indeed, (as I first

announced, and Fabricius agrees with me,) by any manner or way get into

the inner recesses of that organ, much less ascend as high as the ovary,

near the waist or middle of the body, so that besides its peculiar

virtue it might impart a portion of matter to the numerous ova whose

rudiments are there contained. For we know, and are assured by

unquestionable experience, that several ova are fecundated by one and

the same connexion,--not those only that are met with in the uterus and

ovary, but those likewise that are in some sort not yet begun, as we

shall state by and by, and indeed, as we have already had occasion to

assert in our history.

If, therefore, an egg be rendered fruitful by its proper vital

principle, or be endowed with its own inherent fecundating force, whence

or whereby either a common fowl, or a hybrid betwixt the fowl and the

pheasant is produced, and that either male or female, like the father or

the mother, healthy or diseased; we must infallibly conclude that the

egg, even when contained in the ovary, does not live by the vital

principle of the mother, but is, like the youth who comes of age, made

independent even from its first appearance; as the acorn taken from the

oak, and the seeds of plants in general, are no longer to be considered

parts of the tree or herb that has supported them, but things made in

their own right, and which already enjoy life in virtue of a proper and

inherent vegetative power.

But if we now admit that there is a living principle in a fertile egg,

it may become matter of discussion whether it is the same living

principle which already inheres in the egg that will inhere in the

future chick, or whether it is a different one that actuates each? For

it is matter of necessity that we admit the inherence of a certain

principle which constitutes and causes the egg to grow, and which

farther engenders and makes the chick to increase. We have to inquire,

therefore, whether the animating principle of the egg and of the chick

be one and the same, or several and different? And then, were several

vital principles recognized, some appertaining to the egg, others to the

chick, we should next have to inquire: whence and at what epoch the

animating principle of the chick entered it? and what is it in the egg

which causes the cicatricula to dilate before the advent of the living

principle; which draws the eye of the vitellus upwards, as stated, and

produces the colliquament, changes the constitution of the fluids of the

egg, and preordains everything for the construction of the future chick

before there is even a vestige of it to be seen? Or whence shall we say

the aliment fit for the embryo is derived, and by which it is nourished

and made to grow, before it is yet in being? For these acts are seen to

be the work of the vegetative soul of the embryo, and have reference to

the coming pullet, ensuring its nutrition and growth. And again, when

the embryo is begun, or the chick is half formed, what is it which

constitutes that embryo or that chick one and continuous and connex with

the liquids of the egg? What nourishes and makes the chick to grow, and

preserves the fluids that are fit for its nutrition from putrefaction,

and prepares, and liquefies, and concocts them?

If the vital principle be the act of the organic body possessing life

_in potentia_, it seems incredible that this principle can inhere in the

chick before something in the shape of an organized body is extant. Nor

is it more credible that the vital principle of the egg and chick can be

identical, if the vital principle be conservative of that only to which

it belongs; but the egg and the chick are different things, and manifest

dissimilar and even opposite vital acts, in so much so that one appears

to be produced by the destruction of the other. Or should we perchance

maintain that the same principle and cause of life inheres in both, in

the pullet half fashioned, to wit, and the egg half consumed, as if it

were one and a simple act of the same body; or as if from parts

producing one natural body, one soul or vital principle also arose,

which was all in all, as is commonly said, and all in each particular

part? Just as with leaves and fruit conspicuous on the stem of a tree,

wherever a division is made we still say that the principle or first

cause of the slip and of the whole tree is the same; the leaves and the

fruit are, as it were, the form and end, the trunk of the tree the

beginning. So too in a line, wherever a division is made, this will

become the end or boundary of the part behind it, the commencement of

the part before it. And the same thing is seen to obtain in respect of

quality and motion, that is to say, in every kind of transmutation and

generation.

So much at this time upon these topics, which will by and by engage us

at greater length, when we come to speak of the nature of the living

principle of the embryos of animals in general; of its being; of its

accession in respect of the how and the when; and how it is all in all,

and all in each particular part, the same and yet different. Points

which we shall determine from numerous observations.

EXERCISE THE TWENTY-SEVENTH.

_The egg is not the product of the uterus, but of the vital principle._

“As we have said,” says Fabricius,[209] “that the action of the stomach

was to convert the food into chyle, and the action of the testicles to

produce semen, because in the stomach we find chyle, in the testes

semen, so do we definitely assert that the egg is the product of the

uterus of birds, because it is found in this part. The organ and seat of

the generation of eggs is, therefore, intimately known and obvious to

us. And farther, inasmuch as there are two uteri in birds, one superior

and the other inferior, and these are considerably different from one

another, and consequently perform different offices, it is in like

manner clear what particular action is to be ascribed to each. The

superior is devoted to the production of the yelk, the inferior to that

of the albumen and remaining parts, or of the perfect egg, as lies

obvious to sense; for in the superior uterus we never find aught beyond

a multitude of yelks, nor in the inferior uterus, other than entire and

perfect eggs. But these are not all the functions of the uteri as it

appears, but the following are farther to be noted and enumerated, viz.:

the increase of the egg, which succeeds immediately upon its production,

and proceeds until it is perfected and acquires its proper dimensions.

For the fowl does not naturally lay an egg until it has become complete

and has acquired its due dimensions. The actions of the uteri are

consequently the increase as well as the engenderment of the egg; but

increase supposes and includes nutrition, as is obvious. And since all

generation is the effect of the concurrence of two, viz., the agent and

the matter, the agent in the generation of an egg is nothing else than

the instruments or organs aforesaid, to wit, the double uterus; and the

matter is nothing but the blood.”

Now whilst I admit the action of the uterus to be in a manner the

generation of the egg, I by no means allow that the egg is nourished and

increased by this organ. And this, both for the reasons already alleged

by us when we treated of the vital principle of the egg, which is that

which nourishes it, and also because it appears little likely (according

to Aristotle,[210] it is impossible,) that all the internal parts of the

egg, in all their dimensions, should be fashioned and made to increase

by an external agent, such as the uterus is with reference to the egg;

for how, I beseech you, can that which is extrinsic arrange the natural

matter in things that are internal, and supply fresh matter according to

the several dimensions in the place of that which has been lost? How can

anything be affected or moved by that which does not touch it?

Wherefore, without question, the same things happen in the engenderment

of eggs which take place in the beginning of all living things

whatsoever, viz.: they are primarily constituted by external and

preexisting beings; but so soon as they are endowed with life, they

suffice for their own nourishment and increase, and this in virtue of

peculiar inherent forces, innate, implanted from the beginning.

What has already been said of the vital principle appears clearly to

proclaim that the egg is neither the work of the uterus, nor governed by

that organ; for it is manifest that the vegetative principle inheres

even in the hypenemic egg, inasmuch as we have seen that this egg is

nourished and is preserved, increases and vegetates, all of which acts

are indications of the presence of the principle mentioned. But neither

from the mother nor the uterus can this principle proceed, seeing that

the egg has no connexion or union with them, but is free and

unconnected, like a son emancipated from pupillage, rolling round within

the cavity of the uterus and perfecting itself, even as the seeds of

plants are perfected in the bosom of the earth, viz., by an internal

vegetative principle, which can be nothing else than the vegetative

soul.

And it will appear all the more certain that it is possessed of a soul

or vital principle, if we consider by what compact, what moving power,

the round and ample yelk, detached from the cluster of the ovary,

descends through the infundibulum--a most slender tube composed of a

singularly delicate membrane, and possessed of no motory fibres--and

opening a path for itself, approaches the uterus through such a number

of straits, arrived in which it continues to be nourished, and grows and

is surrounded with albumen. Now as there is no motory organ discoverable

either in the ovary which expels the vitellus, or in the infundibulum

which transmits, or in the uterus which attracts it, and as the egg is

not connected with the uterus, nor yet with the ovary by means of

vessels, nor hangs from either by an umbilical cord, as Fabricius truly

states, and demonstrates most satisfactorily, what remains for us

contemplating such great and important processes but that we exclaim

with the poet:[211]

’Tis innate soul sustains; and mind infused

Through every part, that actuates the mass.

And although the rudiments of eggs, which we have said are mere specks,

and have compared to millet seeds in size, are connected with the ovary

by means of veins and arteries, in the same manner as seeds are attached

to plants, and consequently seem to be part and parcel of the fowl, and

to live and be nourished after the manner of her other parts, it is

nevertheless manifest, that seeds once separated from the plants which

have produced them, are no longer regarded as parts of these, but like

children come of age and freed from leading-strings, they are maintained

and governed by their own inherent capacities.

But of this matter we shall speak more fully, when we come to treat of

the soul or living principle of the embryo in general, and of the

excellence and divine nature of the vegetative soul from a survey of its

operations, all of which are carried on with such foresight, art, and

divine intelligence; which, indeed, surpass our powers of understanding

not less than Deity surpasses man, and are allowed, by common consent,

to be so wonderful that their ineffable lustre is in no way to be

penetrated by the dull edge of our apprehension.

What shall we say of the animalcules which are engendered in our bodies,

and which no one doubts are ruled and made to vegetate by a peculiar

vital principle (anima)? of this kind are lumbrici, ascarides, lice,

nits, syrones, acari, &c.; or what of the worms which are produced from

plants and their fruits, as from gall-nuts, the dog-rose, and various

others? “For in almost all dry things growing moist, or moist things

becoming dry, an animal may be engendered.”[212] It certainly cannot be

that the living principles of the animals which arise in gall-nuts

existed in the oak, although these animals live attached to the oak, and

derive their sustenance from its juices. In like manner it is credible

that the rudiments of eggs exist in the ovarian cluster by their proper

vital principle, not by that of the mother, although they are connected

with her body by means of arteries and veins, and are nourished by the

same food as herself. Because, as we have stated in our history, all the

vitellary specks do not increase together, like the grapes of a bunch,

or the corns of an ear of wheat, as if they were pervaded by one common

actuating force or concocting and forming cause; they come on one after

another, as if they grew by their own peculiar energy, each that is most

in advance severing itself from the rest, changing its colour and

consistence, and from a white speck becoming a yelk, in regular and

determinate sequence. And what is more particularly astonishing is that

which we witness among pigeons and certain other birds, where two yelks

only come to maturity upon the ovarian cluster together, one of which,

for the major part, produces a male, the other a female, an abundance of

other vitellary specks remaining stationary in the ovary, until the term

comes round for two more to increase and make ready for a new birth. It

is as if each successive pair received fertility from the repeated

addresses of the male; as if the two became possessed of the vital

principle together; which, once infused, they forthwith increase

spontaneously, and govern themselves, living of their own not through

their mother’s right. And, in sooth, what else can you conceive working,

disposing, selecting, and perfecting, as respects this pair of vitellary

papulæ and none others, but a peculiar vital principle? And although

they attract nourishment from the mother, they still do so no otherwise

than as plants draw food from the ground, or as the embryo obtains it

from the albumen and vitellus.

Lastly, since the papula existing in the ovary receives fecundity from

the access of the male, and this of such a kind that it passes into the

form and likeness of the concurring male, whether he were a common cock

or a pheasant, and there is as great diversity in the papulæ as there

are males of different kinds; what shall we hold as inherent in the

papulæ themselves, by whose virtue they are distinguished from one

another and from the mother? Undoubtedly it must be the vital principle

by which they are distinguished both from each other and from the

mother.

It is in a similar manner that fungi and parasitic plants live upon

trees. And besides, we in our own bodies frequently suffer from cancers,

sarcoses, melicerides, and other tumours of the same description, which

are nourished and grow as it seems by their own inherent vegetative

principle, the true or natural parts of the body meantime shrinking and

perishing. And this apparently because these tumours attract all the

nourishment to themselves, and defraud the other parts of the body of

their nutritious juices or proper genius. Whence the familiar names of

phagedæna and lupus; and Hippocrates, by the words το θεῑον, perhaps

understood those diseases which arise from poison or contagion; as if in

these there was a certain vitality and divine principle inherent, by

which they increase and through contagion generate similar diseases even

in other bodies. Aristotle[213] therefore says: “all things are full of

soul;” and elsewhere he seems to think that “even the winds have a kind

of life, and a birth and a death.”[214] But there is no doubt that the

vitellus, when it is once cast loose and freed from all connexion with

the fowl, during its passage through the infundibulum and its stay in

the cavity of the uterus, attracts a sluggish moisture to itself, which

it absorbs, and by which it is nourished; there too it surrounds itself

with albumen, furnishes itself with membranes and a shell, and finally

perfects itself. All of which things, rightly weighed, we must needs

conclude that it is possessed by a proper vital principle (anima).

EXERCISE THE TWENTY-EIGHTH.

_The egg is not produced without the hen._

Leaving points that are doubtful, and disquisitions bearing upon the

general question, we now approach more definite and obvious matters.

And first, it is manifest that a fruitful egg cannot be produced without

the concurrence of a cock and hen: without the hen no egg can be formed;

without the cock it cannot become fruitful. But this view is opposed to

the opinion of those who derive the origin of animals from the slime of

the ground. And truly when we see that the numerous parts concurring in

the act of generation,--the testes and vasa deferentia in the male, the

ovarium and uterus and blood-vessels supplying them in the female--are

all contrived with such signal art and forethought, and everything

requisite to reproduction in a determinate direction--situation, form,

temperature,--arranged so admirably, it seems certain, as nature does

nothing in vain, nor works in any round-about way when a shorter path

lies open to her, that an egg can be produced in no other manner than

that in which we now see it engendered, viz., by the concurring act of

the cock and hen. Neither, in like manner, in the present constitution

of things, can a cock or hen ever be produced otherwise than from an

egg. Thus the cock and the hen exist for the sake of the egg, and the

egg, in the same way, is their antecedent cause; it were therefore

reasonable to ask, with Plutarch, which of these was the prior, the egg

or the fowl? Now the fowl is prior by nature, but the egg is prior in

time; for that which is the more excellent is naturally first; but that

from which a certain thing is produced must be reputed first in respect

of time. Or we may say: this egg is older than that fowl (the fowl

having been produced from it); and, on the contrary, this fowl existed

before that egg (which she has laid). And this is the round that makes

the race of the common fowl eternal; now pullet, now egg, the series is

continued in perpetuity; from frail and perishing individuals an

immortal species is engendered. By these, and means like to these, do we

see many inferior or terrestrial things brought to emulate the

perpetuity of superior or celestial things.

And whether we say, or do not say, that the vital principle (anima)

inheres in the egg, it still plainly appears, from the circuit

indicated, that there must be some principle influencing this revolution

from the fowl to the egg and from the egg back to the fowl, which gives

them perpetuity. Now this, according to Aristotle’s views,[215] is

analogous to the element of the stars; and is that which makes parents

engender, and gives fertility to their ova; and the same principle,

Proteus like, is present under a different form, in the parents as in

the eggs. For, as the same intelligence or spirit which incessantly

actuates the mighty mass of the universe, and compels the same sun from

the rising to the setting, in his passage over the various regions of

the earth, so also is there a vis enthea, a divine principle inherent in

our common poultry, showing itself now as the plastic, now as the

nutritive, and now as the augmentative force, though it is always and at

all times present as the conservative and vegetative force, and now

assumes the form of the fowl, now that of the egg; but the same virtue

continues to inhere in either to eternity. And although some animals

arise spontaneously, or as is commonly said from putrefaction, and some

are produced from the female alone, for Pliny[216] says: “in some

genera, as in certain fishes, there are no males, every one taken being

found full of roe;” still whatever is produced from a perfect egg is so

in virtue of the indispensable concurrence of male and female.

Aristotle[217] consequently says: “the grand principles of generation

must be held to be the male and the female;” the first two principles of

the egg are therefore the male and the female; and the common point or

conception of these is the egg, which combines the virtues of both

parents. We cannot, in fact, conceive an egg without the concurrence of

a male and female fowl, any more than we can conceive fruit to be

produced without a tree. We therefore see individuals, males as well as

females, existing for the sake of preparing eggs, that the species may

be perennial, though their authors pass away. And it is indeed obvious,

that the parents are no longer youthful, or beautiful, or lusty, and

fitted to enjoy life, than whilst they possess the power of producing

and fecundating eggs, and, by the medium of these, of engendering their

like. But when they have accomplished this grand purpose of nature, they

have already attained to the height, the ακμὴ of their being,--the final

end of their existence has been accomplished; after this, effete and

useless, they begin to wither, and, as if cast off and forsaken of

nature and the Deity, they grow old, and, a-weary of their lives, they

hasten to their end. How different the males when they make themselves

up for intercourse, and swelling with desire are excited by the venereal

impulse! It is surprising to see with what passion they are inflamed;

and then how trimly they are feathered, how vainglorious they show

themselves, how proud of their strength, and how pugnacious they prove!

But, the grand business of life accomplished, how suddenly, with failing

strength and pristine fervour quenched, do they take in their swelling

sails, and, from late pugnacity, grow timid and desponding! Even during

the season of jocund masking in Venus’s domains, male animals in general

are depressed by intercourse, and become submissive and pusillanimous,

as if reminded that in imparting life to others, they were contributing

to their own destruction. The cock alone, replete with spirit and

fecundity, still shows himself alert and gay; clapping his wings, and

crowing triumphantly, he sings the nuptial song at each of his new

espousals! yet even he, after some length of time in Venus’s service,

begins to fail; like the veteran soldier, he by and by craves discharge

from active duty. And the hen, too, like the tree that is past bearing,

becomes effete, and is finally exhausted.

EXERCISE THE TWENTY-NINTH.

_Of the manner, according to Aristotle, in which a perfect and fruitful

egg is produced by the male and female fowl._

Shortly before we said that a fruitful egg is not engendered

spontaneously, that it is not produced save by a hen, and by her only

through the concurrence of the cock. This agrees with the matter of the

following sentence of Aristotle:[218] “The principles of generation have

particular reference to male and female; the male as supplying the

original of motion and reproduction; the female as furnishing the

matter.”

In our view, however, an egg is a true generative seed, analogous to the

seed of a plant; the original conception arising between the two

parents, and being the mixed fruit or product of both. For as the egg is

not formed without the hen, so is it not made fruitful without the

concurrence of the cock.

We have therefore to inquire how the egg is produced by the hen and is

fertilized by the cock; for we have seen that hypenemic eggs, and these

animated too, are engendered by the hen, but that they are not prolific

without the intercourse of the cock. The male and the female

consequently, both set their mark upon a fruitful egg; but not, I

believe, in the way in which Aristotle imagines, viz.: that the male

concurs in the motion and commencement of generation only, the female

supplying nothing but the matter, because the contrary of this is

obvious in hypenemic eggs. And although it be true as he says: “That

male and female differ in respect of reason, because the faculty of each

is different, and, in respect of sense, because certain parts differ

likewise. The difference according to reason boasts this distinction,

that the male has the power of engendering in another; the female has

only the power of engendering in herself; whereby it comes that that

which is engendered is produced, this being contained in that which

engenders. But as males and females are distinguished by certain

faculties and functions, and as an instrument is indispensable to every

office, and the parts of the body are adapted as instruments of the

functions, it was necessary that certain parts should be set aside for

purposes of procreation and coition, and these differing from one

another, whereby the male differs from the female.”

It does not, however, follow from thence, that what he appears inclined

to infer is correct, where he says: “The male is the efficient agent,

and by the motion of his generative virtue (genitura), creates what is

intended from the matter contained in the female; for the female always

supplies the matter, the male the power of creation, and this it is

which constitutes one male, another female. The body and the bulk,

therefore, are necessarily supplied by the female; nothing of the kind

is required from the male; for it is not even requisite that the

instrument, nor the efficient agent itself, be present in the thing that

is produced. The body, then, proceeds from the female, the vital

principle (anima) from the male; for the essence of every body is its

vital principle (anima).” But an egg, and that animated, is engendered

by the pullet without the concurrence of the male; whence it appears

that the hen too, or the female, may be the efficient agent, and that

all creative force or vital power (anima) is not derived exclusively

from the male. This view indeed appears to be supported by the instance

quoted by Aristotle himself, for he says:[219] “Those animals not of the

same species, which copulate, (which those animals do that correspond

in their seasons of heat and times of uterogestation, and do not differ

greatly in their size,) produce their first young like themselves, but

partaking of the species of both parents; of this description is the

progeny of the fox and dog, of the partridge and common fowl, &c.; but

in the course of time from diversity results diversity, and the progeny

of these different parents at length acquires the form of the female; in

the same way as foreign seed is changed at last in conformity with the

nature of the soil, which supplies matter and body to the seed.”

From this it appears, that in the generation of the partridge with the

common fowl it is not the male alone that is efficient, but the female

also; inasmuch as it is not the male form only, but one common or

subordinate that appears in the hybrid, as like the female as it is like

the male in vital endowment (anima), and bodily form. But the vital

endowment (anima) is that which is the true form and species of an

animal.

Farther, the female seems even to have a superior claim to be considered

the efficient cause: “In the course of time,” says the philosopher, “the

progeny of different species assumes the form of the female;” as if the

semen or influence of the male were the less powerful; as if the species

impressed by him disappeared with the lapse of time, and were expelled

by a more powerful efficient cause. And the instance from the soil

confirms this still farther: “for foreign seeds are changed at length

according to the nature of the soil.” Whence it seems probable that the

female is actually of more moment in generation than the male; for, “in

the world at large it is admitted that the earth is to nature as the

female or mother, whilst climate, the sun, and other things of the same

description, are spoken of by the names of generator and father.”[220]

The earth, too, spontaneously engenders many things without seed; and

among animals, certain females, but females only, procreate of

themselves and without the concurrence of the male: hens, for example,

lay hypenemic eggs; but males, without the intervention of females,

engender nothing.

By the same arguments, indeed, by which the male is maintained to be the

principle and prime ‘efficient’ in generation, it would seem that the

female might be confirmed in the prerogative of ὲνεργεία or efficiency.

For is not that to be accounted efficient in which the reason of the

embryo and the form of the work appear; whose obvious resemblance is

perceived in the embryo, and which, as first existing, calls forth the

other? Since, therefore, the form, cause, and similitude inhere in the

female not less--and it might even be said that they inhere more--than

in the male, and as she also exists previously as prime mover, let us

conclude for certain that the female is equally efficient in the work of

generation as the male.

And although Aristotle[221] says well and truly, “that the conception or

egg receives no part of its body from the male, but only its form,

species, and vital endowment (anima), and from the female its body

solely, and its dimensions,” it is not yet made sufficiently to appear

that the female, besides the matter, does not in some measure contribute

form, species, and vital endowment (anima). This indeed is obvious in

the hen which engenders eggs without the concurrence of a male; in the

same way as trees and herbs, in which there is no distinction of sexes,

produce their seeds. For Aristotle himself admits,[222] that even the

hypenemic egg is endowed with a vital principle (anima). The female must

therefore be esteemed the efficient cause of the egg.

Admitting that the hypenemic egg is possessed of a certain vital

principle, still it is not prolific; so that it must further be

confessed that the hen of herself is not the efficient cause of a

perfect egg, but that she is made so in virtue of an authority, if I may

use the word, or power required of the cock. For the egg, unless

prolific, can with no kind of propriety be accounted perfect; it only

obtains perfection from the male, or rather from the female, as it were

upon precept from the male; as if the hen received the art and reason,

the form and laws of the future embryo from his address. And so in like

manner the female fowl, like to a fruitful tree, is made fertile by

coition; by this is she empowered not only to lay eggs, but these

perfect and prolific eggs. For although the hen have as yet no rudiments

of eggs prepared in her ovary, nevertheless, made fertile by the

intercourse of the male, she by and by not only produces them there, but

lays them, teeming with life, and apt to produce embryos. And here that

practice of the poor folks finds its application: “Having hens at home,

but no cock, they commit their females to a neighbour’s male for a day

or two; and from this short sojourn the fecundity of the whole of the

eggs that will be laid during the current season is secured.”[223] Not

only are those eggs which are still nothing more than yelk and have no

albumen, or which exist only as most minute specks in the ovary, but

eggs not yet extant, that will be conceived long afterwards, rendered

fertile by the same property.

EXERCISE THE THIRTIETH.

_Of the uses of this disquisition on fecundity._

This disquisition on the inherent qualities of the egg and the cause of

its fecundity, is alike in point of difficulty and subtlety, but of the

highest importance. For it was imperative on us to inquire what there

was in the conception, what in the semen masculinum, and what in the

female fowl, which render these fertile; and what there is in the

fruitful cock which makes him differ from a bird that is barren. Is the

cause identical with that which we have called the vital principle

(anima) in the embryo, or it is a certain portion of the vegetative

principle? Because, in order to apprehend the entire cause of

generation, it is of much moment that the first cause be understood; for

science is based upon causes, especially first causes, known. Nor is

this inquiry less important in enabling us to understand the nature of

the vital principle (anima). These questions, indeed, rightly

apprehended, not only are Aristotle’s opinions of the causes of

generation refuted or corrected, but all that has been written against

him is easily understood.

We ask, therefore, whether it is the same thing or something different,

which in the rudimentary ovum, yelk, egg, cock and hen, or her uterus,

confers fruitfulness? In like manner in what respect does this something

agree or differ in each? Still farther, is it a substance whence the

fecundating virtue flows?--it appears susceptible of powers, faculties,

and accidents. Likewise, is it corporeal also? for that which engenders

mixture appears to be mixed:--the progeny has a common resemblance to

the mother and father, and exhibits a doubtful nature when animals of

dissimilar species, such as the pheasant and common fowl, engender;

that, too, appears to be corporeal which suffers from without, and to

such an extent that not only are weakly embryos procreated, but even

deformed and diseased ones, obnoxious to the vices as well as to the

virtues of their progenitors.

With respect to these several particulars we may farther be permitted to

doubt whether that which confers fecundity is engendered or accrues from

without? Whether, to wit, it is transfused from the egg to the embryo

and chick, from the hen to the egg, from the cock to the hen? For there

appears to be something that is transferred or transfused, something,

namely, which from the cock is transfused into the hen, and from her is

given to the uterus, to the ovary, to the egg; something which passing

from the seed to the plant, is rendered again by the plant to the seed,

and imparts fecundity. Because there is this common to all things which

are perpetuated by generation, that they derive their origin from seed.

But the semen, the conception, and the egg, are all of the same

essential kind, and that which confers fertility on these is one and the

same, or of like nature; and this indeed is divine, the analogue of

heaven, possessed of art, intelligence, foresight. This is plainly to be

seen from its admirable operations, artifices, and wisdom, where nothing

is vain, or inconsiderate, or accidental, but all conduces to some good

end.

Of the general principles and science of this subject we shall treat

more at length in the proper place; we have now said as much

incidentally as seems necessary, the occasion having presented itself

along with our consideration of the hen’s egg, namely, how many things

inhere which induce fertility, and how this is induced, and whether it

is an affection, a habit, a power, or a faculty; whether it is to be

regarded as a form and substance, as a something contained generally, or

only in some particular part--since it is quite certain that a hypenemic

egg is a perfect egg in so far as each sensible particular is concerned,

and yet is barren; the uterus in like manner, and the hen and the cock

are all perfect; yet are they severally sterile, as being without that

which confers fecundity. All of these matters we shall advert to after

we have shown what and how two principles, male and female, concur in

the production of the egg and the process of generation, and in what way

both may be regarded as efficient causes and parents of the egg.

EXERCISE THE THIRTY-FIRST.

_The egg is not produced by the cock and hen in the way Aristotle would

have it._

It is certain, as we have said, that a fruitful egg is not produced

without the concurrence of the cock and hen; but this is not done in the

way that Aristotle thought, viz. by the cock as prime and sole ‘agent,’

the hen only furnishing the ‘matter.’ Neither do I agree with him when

he says:[224] “When the semen masculinum enters the female uterus, it

coagulates the purest portion of the catamenia;” and shortly afterwards:

“but when the catamenia of the female has set in the uterus, it forms,

with the semen masculinum, a coagulum like that of milk; for curd is

milk containing vital heat, which attracts like particles around it, and

combines and coagulates them; and the semen of the male (genitura) bears

the same affinity to the nature of the catamenia. For milk and the

menstrual discharge are of the same nature. When coagulation has taken

place, then an earthy humour is excreted and is drawn around, and the

earthy portion drying up, the membranes are produced both as matter of

necessity, and also for a certain purpose. And these things take place

in the same manner in all creatures, both oviparous and viviparous.”

But the business in the generation of an egg is very different from

this; for neither does the semen, or rather the ‘geniture,’ proceeding

from the male in the act of intercourse, enter the uterus in any way,

nor has the hen, after she conceives, any particle of excrementitious

matter, even of the purest kind, or any blood in her uterus which might

be fashioned or perfected by the discharge of the male. Neither are the

parts of the egg, the membranes, to wit, and the fluids, produced by

any kind of coagulation; neither is there any thing like curdled milk to

be discovered in the uterus, as must be obvious from the foregoing

exercises. It follows, therefore, and from thence, that neither does the

conception, whence the animal springs, as the herb arises from a

fruitful seed, comport itself in the manner Aristotle imagined, since

this takes place in viviparous animals in the same way as the egg is

formed in oviparous animals, as he himself avows, and as shall be

demonstrated by and by in our observations. Because it is certain that

eggs of every description--prolific and barren--are engendered and

formed by the hen singly, but that fecundity accrues from the male

alone;--the cock, I say, contributes neither form nor matter to the egg,

but that only by which it becomes fertile and fit to engender a chick.

And this faculty the cock confers by his semen (genitura), emitted in

the act of intercourse, not only on the egg that is already begun, or is

already formed, but on the uterus and ovary, and even on the body of the

fowl herself, in such wise that eggs which have yet to be produced,

eggs, none of the matter of which yet exists either in the ovary or in

any other part of the body, are thence produced possessed of fecundity.

EXERCISE THE THIRTY-SECOND.

_Nor in the manner imagined by physicians._

Conception, according to the opinion of medical men, takes place in the

following way: during intercourse the male and female dissolve in one

voluptuous sensation, and eject their seminal fluids (genituræ) into the

cavity of the uterus, where that which each contributes is mingled with

that which the other supplies, the mixture having from both equally the

faculty of action and the force of matter; and according to the

predominance of this or of that geniture does the progeny turn out male

or female. It is farther imagined that immediately after the

intercourse, the active and passive principles cooperating, something of

the conception is formed in the uterus. For contrary to the

Aristotelians, they maintain that the male is no more the efficient

cause of generation than the female, but some mixture of the two; and

that neither the menstrual blood nor its purest part is the prime matter

of the conception, but the spermatic fluid; whence the first particles

or their rudiments are spoken of as spermatic, these at an after period

being nourished and made to increase through the blood.