_Theophilus_ of Antioch:--“He directed these words, _Let us make man_,

to none other than his own Word and his own Wisdom.”[177]

_Irenæus_:--“His Word and Wisdom, his Son and Spirit, are always

present with him, to whom also he spake, saying, _Let us make man_,

&c.”[178] Again:--“Man was fashioned after the image and likeness of

the uncreated God, the Father willing his creation, the Son ministering

and forming him, the Holy Ghost nourishing and increasing him.”[179]

_Tertullian_:--“Nay, because his Son is ever present with him, the

second person, his Word; and the third, the Spirit in the Word;

therefore he spake in the plural, _Let us make man in our image_.”[180]

_Novatian_:--“Who does not acknowledge the Son to be the second person

after the Father, when he reads that it was said to the Son by the

Father, _Let us make man_.”[181]

_Origen_:--“To him also spake he (the Father,) _Let us make man after

our image_.”[182]

_Athanasius_:--“Who is this that God converses with here? To whom are

these notifications and determinations of his pleasure directed? Not

to any of the creatures already made; much less to those things which

were not yet created; but, undoubtedly to some person, who was then

present with the Father, to whom he communicated his councils, and of

whose agency he made use in the creation of them. And who could this

be but his eternal Word? With whom can we conceive the Father holding

his conference, but with his Son, the divine LOGOS, that Wisdom of God,

that was present with him, and acted with him, in the creation of the

world, who was in the beginning with God, and was God? and who saith of

himself, _When he prepared the heavens, I was there; when he appointed

the foundations of the earth, then was I by him, as one brought up with

him_.”

_St. Augustine_:--“Had God said no more than, Let _us make man_, it

might, with some color, be understood as spoken to the angels, whom

the Jews pretend he employed in framing the body of man, and other

creatures; but seeing it immediately follows, _after our image_, it is

highly profane to believe, that man was made after the similitude of

angels; and that the similitude of God and angels is one and the same.”

_St. Ambrose_ speaks to the same purpose:--“God would not speak thus

to his servants, because it is not to be thought, that servants were

partners with their Lord, in his works of creation; or the works with

their Author. And, supposing this should be admitted, that the work was

common to God and angels, yet the image was not common.”

Nay, the second Council of Sirmium, which was held in 351, pronounced

an anathema on all those who denied this. The words of the Council are

these:--“If any say, that the Father did not speak to the Son, when

he said, _Let us make man_, but that he spake to himself, let him be

accursed.”[183]

_Epiphanius_:--“This is the language of God to his Word, and

Only-begotten, as all the faithful believe.”[184] And again he says,

“Adam was formed by the hand of the Father, and the Son, and the Holy

Ghost.”[185]

I observe more at large from _Irenæus_, that he rejects the notion

of the Jews and Heretics, who supposed God spake to his angels.

For disputing against Heretics, who attributed the creation of the

world to angels, and powers separate from the one true God, he says

thus:--“Angels did not make us, nor did they form us; neither was it

in their power to make the image of God: none but the Logos could do

this; no powers distinct from the Father of all things: for God did not

want their assistance in making the things which he had ordained. For

his Word and his Wisdom, the Son and the Holy Ghost, are always with

him; by whom and with whom, he made all things freely, and of his own

accord; to whom also he spake in these words, _Let us make man in our

image and likeness_.”[186]

The testimony of Dr. Kennicott will be respected by those who are

lovers of the truth. “God, says he, being about to create man, is

introduced saying--_Let_ US _make man in_ OUR _image, after our

likeness_; in consequence of which the historian tells us--_so God

created man in his own image, in the image of God created he him_.

It is evident then, that God created man in his own image; this is

mentioned thrice by way of emphasis, and to prevent, if possible, all

possibility of misconstruction. Now what God did, was certainly what

he proposed to do; God created man in his own image, that is, in the

image of the Godhead, and therefore God proposed to create him in the

image of the Godhead. But if God proposed to create him in the image of

the Godhead, the proposal must have been made to the Godhead; because

the words are--_Let us make man in_ OUR _image_. And if the proposal be

here made by God to the Godhead, it is absurd to suppose it made to the

same Person that makes it; and consequently reasonable to think it made

to the other two persons in the Unity of the Godhead.”[187]

The creature now to be made is man.[188] _And God said, Let us make

man._ It is evident that God, by introducing the creation of man with

this peculiar phraseology, intends to impress the mind with a sense of

something extraordinary in his formation. The word אדם _Adam_, which

is translated _man_, is intended to designate the _species_ of animal,

which is vastly superior to all the rest. Though the same kind of

organization may be found in Man, as appears in the lower animals, yet,

as one observes, there is a variety and complication in the parts, a

delicacy of structure, a nice arrangement, a judicious adaptation of

the various members to their great offices and different functions, a

dignity of mien, and perfection of the whole, which are sought for in

vain in all other creatures.

Man is a compound creature, consisting of two distinct essential parts,

body and soul. The union of these constitutes man, for neither of

them when separated can be so denominated. The body was made before

the soul, and formed out of the earth, or, as עפר _âpher_ implies,

the _dust_. “The Lord God formed man of the dust of the ground.” He

afterwards pronounced, _Dust thou art_. This led Solomon to affirm,

“All are of the dust.” The Apostle adds, “The first man was of the

earth, dusty,” as Ainsworth renders it. And we are said to “dwell in

houses of clay,” and to have our “foundation in the dust.” Of the soul

it is said, “God breathed into his nostrils the breath of life:” רוח

חיים _ruach chayim_, the breath of LIVES; i.e. animal, intellectual, and

spiritual. While this breath of God expanded the lungs, and set them to

play, his inspiration gave both spirit, understanding, and felicity.

Thus we see that the soul and the body are not the same thing; the one

is of the earth, the other is from God. The Rabbins say, “The form of

the soul is not compounded of the elements, &c, but is of the Lord

from heaven. Therefore when the material body, which is compounded

of the elements, is separated, and the breath perishes because it is

not found, but with the body, and is needful for the body in all its

actions; this form (i.e. the soul) is not destroyed, &c, but continues

for ever. This is that which Solomon by his wisdom said, ‘Then shall

the dust return unto the earth as it was; and the spirit shall return

unto God who gave it.’”

As the formation of man’s body was effected previously to the infusion

of his soul, we shall attend to the same order, in attempting to

elucidate this important and very interesting subject. The word ייצר

_jitzer_, rendered _he formed_, observes Mr. Benson, is not used

concerning any other creature, and implies a gradual process in the

work, with great accuracy and exactness. It is properly used of potters

forming vessels on the wheel; and Rabbi D. Kimchi says, that, when

used concerning the creation of man, it signifies the formation of his

members. Bishop Patrick intimates, that the body of man was made not of

_dry_, but _moist_ dust; and that this agrees with the Hebrew JITZER,

_formed_, which is used concerning potters, who make their vessels of

_clay_, not of _dry_ earth. Diodorus Siculus says, “Man was made out of

the _slime_, or _mud_, of the Nile.” The word of the Lord once came to

Jeremiah, saying, “Arise, and go down to the potter’s house, and there

I will cause thee to hear my words. Then I went down to the potter’s

house, and, behold, he wrought a work on the wheel. And the word of

the Lord came to me, saying, Behold, as the clay is in the potter’s

hand, so are ye in mine hand!” A scene like this is presented to our

imagination by the words of Moses; the Lord God _formed_, moulded, or

modelled man, as a potter does; we see the work, observes Bishop Horne,

as it were upon the wheel, rising and growing under the hands of the

Divine Artificer!

But, to give the thing a stronger impression on the mind, we will

suppose, says Judge Hale, that this figure rises by degrees, and is

finished part by part, in some succession of time; and that, when

the whole is completed, the veins and arteries bored, the sinews and

tendons laid, the joints fitted, and liquor (transmutable in blood

and juices) lodged in the ventricles of the heart, God infuses into

it a vital principle, whereupon the liquor in the heart begins to

descend, and thrill along the veins, and a heavenly blush arises in the

countenance, such as scorns the help of art, and is above the power of

imitation. The image moves, it walks, it speaks; it moves with such

a majesty, as proclaims it the lord of the creation, and talks with

such an accent and sublimity, as makes every ear attentive, and even

its great Creator enter into converse with it: were we to see all this

transacted before our eyes, I say, we could not but stand astonished at

the thing; and yet this is the exact emblem of man’s formation.

The human body is an excellent piece of workmanship, the shape and

contexture of it admirable, evidently superior to that of all other

animals, and the brightest visible display of the wisdom of the Divine

Architect. The erect posture, figure, stature, use of every part, and

symmetry of the whole, cannot but excite admiration. The fabric of the

eye, the texture of the brain, the configuration of the muscles, the

disposition of the nerves, the construction of the bones; the veins and

arteries, spread throughout the system, the former to return the blood

to the heart, and keep that mysterious engine playing, which throws

the vital fluid through the latter with prodigious force, to animate

and invigorate every part; and many other important particulars, which

we shall now proceed to mention and illustrate, are not only manifest

proofs of the great excellence of this system, but also of the skill,

contrivance, and consummate wisdom of God.

When we take a general view of the animal world, we find the numerous

individuals which compose it, differing considerably in the phenomena

which their economy exhibits. Man, and the higher orders of animals,

are characterized by the constant performance of many complex and

active functions; as respiration, digestion, circulation, &c. Torpid

or hibernating animals display this singular peculiarity, that these

functions are performed for several months, and suspended for several

months, alternately. In another modification of animated matter, namely

the egg, the evidences of vitality would not be exhibited, were not

certain agents applied to evolve them, and, when thus called forth,

they cannot be resumed after long suspension.

Although we are ignorant of the nature of the cause which regulates

the uniform performance of this series of phenomena, thus more or less

extensively displayed in the economy of different animals, we are

nevertheless convinced that such a cause must exist, and are hence

naturally led to distinguish the phenomena by some appropriate term.

Thus observing that the human body, and the bodies of animals which

bear it resemblance, possess locomotive powers, can regulate their

actions, and are capable not only of resisting the laws which govern

inanimate substances, but are enabled to act upon these substances in

direct opposition to these laws, we employ the terms life, vitality,

and vital power, to express the phenomena which thus distinguish

animate from inanimate matter; and in order simply to determine the

import of those terms, we may take a general view of those powers which

a living animal body possesses, and which cease with its existence.

When we compare the living with the dead body, the most striking

circumstance we observe is, that the former was surrounded by the same

chemical agents which are capable of producing the decomposition and

destruction of its soft parts after death; hence it becomes evident,

that its component elements must have been sustained and preserved

by some superior power, which ceases to act at the moment of its

dissolution.

Of all the phenomena which enter into the general idea of life, this

power of self-preservation, or the capability of resisting the laws

which govern inanimate matter, appears the most essential. Without

this principle we can form no conception of life, since it evidently

exists without interruption till the moment of dissolution. It is

this principle which, communicated to an egg, enables it to resist

for a certain period the powers of heat, cold, and putrefaction; a

principle of which the addle or barren egg is entirely devoid. Thus

we find from Mr. J. Hunter’s experiments, that an impregnated egg

is longer in freezing than an addle egg, and every one knows that

the former remains sweet or free from putrefaction much longer. This

principle, which we may consider the most simple state of existence,

is limited in its duration; and for its maintenance, the performance

of no active function is necessary. Hence it continues in the egg

either quiescent for a certain time, and is gradually destroyed; or,

by the agency or stimulus of heat, it acquires the accession of the

power of action, which assimilates inanimate matter into a living

form, and, at length, exhibits in the chick all the phenomena of a

more perfect state of existence, which may be distinguished by the

term active life. In this state, many other phenomena of vitality

are exhibited. Besides the power of self-preservation, an internal

principle of support and reparation, and the power of performing the

important actions of circulation, respiration, digestion, &c, which

are subservient to this principle, is given to animals. These form the

features of what we call life, as it appears in man, and the higher

orders of animals, and certainly constitute its most useful, though not

most essential part. For how little superior is an egg, or a torpid

animal, to vegetable or inanimate matter, till the former contain a

living chick, the latter become an active animal? Thus, though life

may subsist under the quiescent form of self-preservation, it requires

the accession of certain principles, and a power of performing various

important actions, to display its chief characters. The economy then

of an egg, and of a perfect animal, such as man, may be considered

as examples of the most simple and extensive phenomena of vitality.

These, however, are more or less perfectly exhibited in the different

orders of animals. It belongs, for instance, to the economy of certain

animals, which at one time of the year perform active functions,

to become torpid at the approach of winter. In these creatures,

respiration, digestion, and every function which characterizes active

life, is suspended; as in the egg, the principle of self-preservation,

that latent spark of vitality, alone remains, by which we distinguish

torpidity from death. This condition, however, is not of long

continuance; at the approach of summer’s warmth, the power of action is

again called forth, active functions are superadded to the principle of

self-preservation, and life, before quiescent and obscure, now resumes

its most perfect form; or, in other words, the animal just now inert

and motionless, respires again; its heart beats, its blood circulates,

its muscles resume their accustomed motions, and it leaves its winter

quarters in search of food. Having now assumed the nature of an active

animal, the performance of the functions characteristic of that state

(which we shall now proceed to describe) becomes requisite; and, first,

the circulation of a fluid which we call _blood_.[189]

This fluid differs in its appearance in the different orders of

animals, though, in its essential properties there is little variety;

the appearance of the blood in man, and the more perfect animals, is

that of a red fluid, having a certain degree of viscidity, not being

limpid like common water. Though it appears to be a homogenous fluid

whilst circulating, or at the moment it escapes from its vessels, it

is composed of three parts, essentially differing from each other; of

_particles_, upon which the color of the blood depends; of _coagulating

lymph_, which has the property of becoming spontaneously solid under

certain circumstances, and from which various structures in the body

are formed; and of a limpid fluid called _serum_, which dilutes the

coagulating lymph, and fits it for circulating through blood vessels of

a very minute size. In some of the lower orders of animals, however,

the color of the particles of the blood is green, in others white,

corresponding with the color of the animal; in others there is no

color whatever in the blood, so that it is either void of particles,

or they are transparent, so as not to be seen. But this deficiency

must be considered as making no great difference in the blood itself,

as its particles do not appear to be its most essential part. Many

microscopical observations have been made to determine the size of a

single particle of the blood, and according to the observations of

several philosophers, the diameter of a single particle in man has been

computed at the 3,000th part of an inch. The size of the particles in

red blooded animals, is found not to correspond with the size of the

animal. They are as large in the mouse as the elephant, larger in some

insects than in man, smaller in the ox. They are in prodigious numbers,

so as to give color to the blood, and of all its parts appear to be

renewed the most slowly; thus when animals are frequently bled, the

flesh becomes paler and paler.[190]

The next part of the blood, or coagulating lymph, is of the greatest

importance. This constituent part becomes apparent, when blood is drawn

from a vein into a cup, from its power of spontaneously coagulating

into a solid mass, which appears red from a mixture of red particles:

the color of the lymph however is transparent. This coagulation of

the blood differs very essentially from the coagulation of inanimate

substances, and is considered by many physiologists to be the last

exertion of a living principle, which the blood is supposed to possess.

This opinion, although not capable of absolute proof, is rendered

extremely probable from a variety of facts, and by none more than the

analogy between the coagulation of the blood, and the contraction of

the muscles at death. These two actions appear to be influenced in

some degree by the same causes. Thus, sudden death from lightning,

or a blow upon the stomach, prevents the muscles from becoming rigid

after death, and prevents also the coagulation of the blood. Under

these circumstances it remains fluid. Besides violent death, several

circumstances influence its tendency to coagulate and become solid,

such as a great loss of blood--inflammation--pregnancy in females, and

other causes.[191]

The third important part of the blood is the serum. This is limpid like

water, and remains permanently fluid, unless certain substances are

employed to coagulate it, such as alcohol, alum, or a certain degree

of heat. It dilutes the other parts of the blood, so as to reduce the

whole to a proper state of fluidity. It is secreted, or naturally

separated from the blood, and poured out by exhalent vessels in various

cavities and parts of the body, as the chest, abdomen, cellular

membrane, &c. It facilitates the easy motion of the various organs upon

each other, and, when accumulated in large quantities, forms the fluid

of dropsies.

Besides these constituent parts, a quantity of water always circulates

with the blood, varying according to the quantity of fluids taken

in, and regulated in its proportion by the kidneys. Thus if a large

quantity of water is taken into the stomach, particularly if it contain

a little spirit in the form of punch, the kidneys are stimulated to

an increased action, so as to separate from the blood the redundant

quantity. A variety of other substances also are occasionally

introduced into the blood, along with the aliment, alkaline substances

producing their effect upon the nature of the urine, rhubarb on bile

giving it a yellow color, and turpentine or asparagus altering its

odor; all these substances, before passing off by urine, must have been

mixed with the blood, from whence the urine is formed, being in fact

its excrementitious part.[192]

It is necessary for the blood thus formed, to pass to every part of

the body, that it may be converted into the nature of these parts, and

thus become subservient to their growth; that fluids, serving important

purposes in animal bodies, may be separated or secreted from it; and

that the temperature of the body may be equably maintained. The blood,

however, has no power of motion in itself; if it be not propelled by

certain parts of the body, it remains quiescent like any extraneous

fluid.

In two very numerous classes of animals, insects and zoophites, the

motion of the blood is very simple; they are nourished like vegetables,

by the absorption of the fluid, which is prepared in their alimentary

canal, and have no circulation properly so called.

But in man, and the higher orders of animals, a complex apparatus for

the motion of the blood becomes necessary, consisting of an heart,

arteries, and veins. The _heart_ may be considered as the chief agent

in circulation, the general reservoir, and source from whence the blood

flows. It is composed of two principles, one a principle of reception,

the other a principle of propulsion. That cavity of the heart, which

is called its auricle, receives the blood from the veins; the cavity

called its ventricle, propels it through the arteries.

Although the heart in all animals is formed on the same general

principle, and for the same purpose, yet the economy of some animals

admits of a greater simplicity in the conformation of this organ, than

others. The most simple kind of heart is composed of one cavity, with

a tube entering into it, by which it receives the blood, and another

passing out of it, by which the blood is conveyed over the body. The

next simple heart is composed of two cavities, an auricle, which

receives the blood, and propels it into a ventricle, which diffuses it

over the body. Another kind of heart is composed of three cavities;

two auricles, and one ventricle; one auricle receiving the blood from

the lungs, the other from the body generally; the blood from these two

sources is mixed together in a single ventricle. This structure we

find in some amphibious animals, in which it is not necessary that the

blood should circulate with so much influence from the oxygenous part

of the atmosphere, as in other animals. Accordingly we find the heart

adapted to transmit only one half of the blood through the lungs at

each circulation, whilst in more perfect animals the whole mass passes

by this route. The last kind of heart is formed of four cavities, two

auricles and two ventricles, and is the most perfect apparatus as

it is found in man, and quadrupeds generally.--It must, however, be

considered as composed of two distinct parts, or two simple hearts

adhering together, and performing distinct parts of the circulation;

and one part intended to receive the blood from the body, and circulate

it through the lungs; the other part to receive the blood from the

lungs, and propel it over the rest of the body. It is better suited

to the economy of some animals, as the cuttle fish, that these parts

should be separated to a considerable distance from each other. The

reason why the heart is formed of two parts in most animals is, that

it is necessary that the blood should receive the impulse of the heart

twice, first to propel it through the lungs, next to propel it over the

rest of the body.

The blood is conveyed from the heart to every part of the body, by

means of elastic tubes, called _arteries_. These arise from the

ventricles of the heart by two large trunks, which branch out in

every part of the body, into arteries of great minuteness, conveying

the blood from the heart to its most distant parts, so that it is

impossible to wound any part of the body with the finest point,

without opening one of these vessels. This gives a good idea of their

minuteness.

From the minute termination of the arteries, begins a second set of

vessels, the _veins_, which, having a contrary course, return the blood

from every part of the body into the auricles of the heart.

The larger arteries and veins, near the heart, differ very much

from each other in their structure and action. This difference,

however, does not descend to their minute ramifications, which must

be considered as having the same structure, and performing the same

office, the one passing into the other by such imperceptible degrees,

that we cannot mark where the one terminates or the other begins.

If we consider these tubes as subservient to the circulation of the

blood, we shall see the necessity of certain principles entering into

their structure. As the blood is forcibly thrown from the heart, these

vessels must be distended; one of their properties therefore, must be a

capability of being distended, which is given to them by elastic matter

entering into their composition. As the vessels, however, are not to

remain in a distended state, a power of reaction is added, which arises

also out of their elasticity, and assists in propelling the blood

forwards.

Thus the elastic matter allows the vessels to be distended to a certain

degree, and also reduces them to a smaller size. But it is necessary

that the heart shall be assisted considerably, in the circulation

of the blood, by a contractile power of the vessels themselves; and

the same quantity of blood is not to circulate in the same body at

all times, for animals are liable to frequent injuries, by which the

quantities of blood in their bodies may be very suddenly reduced. Hence

the vessels have given to them a further power of contraction to assist

the heart, and accommodate themselves, under certain circumstances, to

a smaller quantity of blood. For this purpose, a muscular structure is

added to them, which is present in largest proportion in the smaller

arteries; by this means, they are enabled so far to withstand the

power of the heart, as to shut their cavities, and prevent the escape

of blood when divided, forming one of the means by which the effusion

of blood is spontaneously checked in living animals. And it may be

remarked, that this power, for the purpose of self-preservation, is

extended to larger arteries in the brute creation; for Mr. Hunter

found, that the flow of blood from the large artery in the neck of an

ass was checked by an exertion of this power, whilst every one knows

that its division in man is fatal.

Besides these parts, arteries have an internal lining, which is

perfectly smooth, and of considerable density, that the blood may

circulate with as little resistance, and be contained as completely as

possible within its proper channels.

The same observations will apply to the veins, though some of their

properties are less strongly marked. They possess an elastic power

capable of distension and reaction, a muscular structure endowed with

contractility, and an internal lining over which the blood circulates

with as little resistance as possible. By these powers the blood

is circulated through every part of the body with great velocity.

According to the best calculations, the heart alone exerts a power

equal to the pressure of 51½ pounds, which propels the blood through

the arteries at the velocity of 149 feet in a minute; in which time it

expels from its cavities about 160 ounces.

Thus all animals are provided with an organ for propelling the blood,

by certain channels, to the different parts of the body; but, as the

functions of these parts are various, they require to be visited by

very different proportions of blood, according to their activity or

powers of life. Some parts of the body may be said to be inert, and

merely possessed of a principle of life, to connect them with the

other organs of the body, as parts of a living system, and to enable

them to go through certain processes in their healthy and diseased

states. Other parts are formed for active functions, and possess great

sensibility. It is accordingly observed, that a smaller quantity of

blood is distributed to bones, tendons, and similar inert parts, than

to muscles and glands, whose exertions are more considerable.

This then is the general apparatus in perfect animals, by which the

blood performs its circulation through the various parts of the body,

but during its course it is subject to constant exhaustion from various

sources. It is converted in its passage into the nature of all the

component parts of the body, and has the different secreted fluids

derived from it, and these processes go on with more activity in a

young, than an adult person: hence we see the necessity of a constant

supply of materials to the blood, and this in the greatest proportion

at an early period of life.

Animals are furnished with the means of this supply, by their power of

converting animal and vegetable substances into the nature of blood, by

a process called _digestion_. Some animals are led by their nature to

live on vegetable food, others on animal food only, whilst others can

subsist on either, or any mixture of both.[193] The digestive powers

of man fit him for any proportion of animal or vegetable foods, and

are the most perfect of all animals. Other creatures may be said to be

confined to a certain district, but the curiosity of man is to lead him

over the whole world, and frequently place him in situations where only

one kind of food is attainable.

The first change which takes place in the food, in order that it shall

be converted into the nature of the blood, is its division into smaller

parts, by the teeth or gizzards of animals. It is then passed into

the stomach, where it remains for some time exposed to the action of

a fluid, formed in the stomach, which is called gastric juice. This

possesses a very strong power of coagulating and dissolving various

animal and vegetable substances. As far as we know, it acts on the

principle of any other solvent, for it produces the same change in

substances out of the body, or even within the body after death. It

frequently happens, for instance, when a person has been killed, by

accident, in full health, that, on inspection, the stomach is found

dissolved, and reduced to a gelatinous mass in several parts, arising

from the action of the gastric juice, which had been formed in it

before death. The gastric juice, however, cannot act upon living

substances: hence the stomach resists its action, and worms sometimes

reside and are even generated in the stomach. Every substance capable

of being acted upon in the stomach, is reduced, by the solvent power

of the gastric juice, into a pulpy mass, which has been called chyme,

the exact chemical properties of which have not been ascertained; in

this state it is by degrees transferred into the beginning of the small

intestines, where it is mixed with the bile and pancreatic fluid, and

undergoes a change into a milky fluid, which is called chyle. It is

then diffused by an undulating motion of the intestines over their

inner surface, that it may be absorbed, and carried into the general

mass of blood.

As far as has yet been ascertained by experiment, the chyle of animals,

most opposite to each other in their food, structure, and habits of

life, is so much alike as to have no distinguishable difference. The

chyle of a Dog, or Wolf, differs in nothing from that of a Sheep or

an Ox. This would appear surprising, were it not ascertained that

almost every alimentary matter undergoes a chemical change before it

is converted into chyle, and that the ultimate analysis of either

animal or vegetable matter presents us with the same elements as those

of the blood, which, though only three or four in number, are capable

of forming the various substances of which the body is composed, by

combining with each other, and in different proportions. There is,

however, this difference observable in the chyle, that in reptiles and

insects it is transparent like lymph.

The lacteals are the vessels by which the chyle is absorbed from the

intestines: they form small processes on the internal surface of the

intestines like the pile of velvet, which are hence called villi.

A small portion of chyle being received into their open mouths, is

propelled by successive contractions of these vessels into their large

trunk, the _thoracic duct_, from whence it is poured into a great

vein near the heart, and, by circulating through the lungs, probably

receives its final change into blood; and this change would seem to

be easily effected, as the chyle already possesses the principal

properties of blood, being formed of particles swimming in a thinner

fluid, and having a power of coagulating spontaneously.[194]

This is the apparatus by which the food is digested in man so as to

replenish the blood; but the digestive organs of different animals

exhibit considerable varieties, some being more simple, others more

complex in their structure, adapted to the kind of food with which the

animal is nourished. Ruminating animals, or animals which chew the

cud, such as the Cow, have several stomachs, and the food undergoes

mastication several times, at each time being passed into a different

stomach, before being finally acted upon by the gastric juice, after

which it is transmitted through a long tract of intestines. This is an

example of the most complex digestive organ fitted to act upon hard

and fibrous food, which must be subjected to the action of several

menstrua preparatory to its being acted upon by the gastric juice.

In birds who live on grain as has been noticed, we meet with a

different apparatus to prepare it to be acted upon by the gastric

juice. The food first passes into the crop, which forms a kind of

reservoir from whence it may pass by degrees into the gizzard, by which

the grain is ground into small particles, before it is transmitted into

the stomach: and it is surprising with how great power the gizzard acts

for this purpose. The Abbé Spallanzani introduced a garnet, which is a

very hard and angular stone, into the gizzard of a Wood-Pigeon, and, in

the course of a day, it was ground perfectly smooth, by the action of

the gizzard. He also introduced a leaden ball stuck full of tin points,

and another with fine lancets, into the gizzard of a Turkey, and in

about 18 hours, the whole of the points were rubbed down. The gizzard

also possesses an amazing power of compression. Raumeur introduced into

the gizzard of a Turkey tubes of tinned iron, seven lines in length,

and two in diameter, closed with solder at each end; some were indented

by the action of the gizzard, and others crushed flat. Similar tubes,

introduced into the teeth of a vice, required the weight of about 440

lb. to produce the same effect. The gizzard thus reduces into small

particles whatever food the animal selects, that it may be more readily

acted upon by the gastric juice in the stomach; for the gastric juice

acts like any other solvent, and therefore acts most advantageously

when the food is reduced into small parts.--The digestive organs

of some of the lower orders of animals form a striking contrast to

these. In the most simple apparatus with which we are acquainted, the

stomach and the intestines are composed of a simple bag which has but

one opening, which serves both to receive the food, and discharge the

excrement. It composes in fact the whole bulk of a fresh-water Polypus.

In these animals the chyle is absorbed by small vessels in the sides of

the bag, and is conveyed to every part of the body.

Thus we find that the supply of materials to the blood is commensurate

to its exhaustion, that in young animals where a more active process

of formation is going on, a larger proportion of food is requisite,

and more chyle formed; this, however, is not all that is necessary

to prepare the blood for its important purposes within the body. The

blood, by passing through the various parts of the body, is so changed

by the abstraction of certain properties, as to render it unfit for

circulation, which implies the necessity of an organ, which may restore

to the blood its requisite qualities. This office is performed by

_respiration_, that function in animals by which the blood receives the

influence of atmospherical air.

There is a great variety in the structure of the organ for exposing the

blood to the air, suited to the mode of life in different animals. In

man and quadrupeds generally the lungs serve this purpose; they are

composed of a number of blood vessels spread out upon minute air cells,

which communicate with and receive the air by means of the trachea

or windpipe, in consequence of the expansion of the chest by certain

muscular powers. These vessels and cells are connected together by

cellular membrane, so as to form a spongy mass called lungs, which are

commonly placed in the chests of animals.--But besides this kind of

organ, which in birds is very large, they have air bags, or appendages

to the lungs, diffused through various parts of the body; even some

of their long bones contain nothing but air, and communicate with the

lungs. It was from a knowledge of this fact that Mr. J. Hunter made

a Turkey breathe by its wings, by making an opening into their large

bones, and closing the animal’s mouth.

In Fish, the gills serve the purpose of lungs. They are composed of

a number of processes arising from cartilages, having distributed

upon them minute blood-vessels, which receive the influence of air

contained in water: and hence distilled water, which contains little

air, destroys fish, in the same manner as the exhausted receiver of an

air pump does a breathing animal.

There is another mode of conveying air for the use of the blood in many

insects, by means of a number of tubes or spiracula: these receive

the external air, and, by ramifying in the body of the animal, convey

its influence to the blood. Thus these animals may be said to respire

like vegetables, throughout the whole of their surface, by vessels

which introduce the air at different points into their bodies. In some

insects the rectum forms the principal organ of respiration, and, in

the class of animals called Zoophites, there are no visible organs of

respiration.

These different modifications, in the respiratory organs of the higher

and lower orders of animals, are all formed with the same intention,

viz. that the blood may be exposed more or less to atmospherical

air. In consequence of this the blood undergoes a process similar to

combustion, which extracts from it a part of its carbon, in the form of

carbonic acid, and by this means increases the relative proportion of

its remaining elements. The inspired air at the same time is deprived

of a part of its oxygen, which is the elastic fluid which commonly

supports respiration. All the corresponding effects produced upon

the blood are not yet fully explained. But by this means the color

of the blood is changed from a dark to a florid red, it acquires the

power of exciting the action of the heart, and is fitted for its

various purposes within the body.[195] By these organs, respiration

is performed more or less extensively in the different orders of

animals, corresponding in a great degree, to their activity, digestive

powers, and the heat maintained in their bodies. Birds, whose extensive

respiratory organs consume a larger quantity of air, are capable

of greater exertion; make more frequent meals than quadrupeds, and

maintain a superior temperature. Quadrupeds hold a middle place between

birds and reptiles. Respiration appears in the class of reptiles, as

Frogs and Toads, to be a subordinate function only; they can exist

without it nearly as long as they please; at the same time they make

very long fasts, and the heat of their bodies is more variable and

lower than quadrupeds; hence they are called cold blooded animals.

Their other habits accord well with their organs of respiration. They

generally live in impure air, their motions are languid, and they pass

a great part of their existence in a state of torpidity.

A subordinate use of respiration in most animals, is the formation of

the voice: for this purpose there are membranes stretched across the

narrow part of the windpipe, which are thrown into a state of vibration

by the current of air: the vibrations thus produced, being modified by

other accessory parts, produce the voice. In many animals, however,

it is produced by a very different mechanism. Some animals employ the

friction of certain elastic parts of the body, as Grasshoppers and

Crickets; others employ the vibration of certain parts in the air,

whilst others impress a rapid motion on portions of air inclosed in

certain parts of their bodies.

There is a particular part of the heart in man, intended merely to

propel the blood, which passes through the lungs to receive the

influence of the air; this is the right ventricle; from whence the

blood passes, by the pulmonary artery, through the minute vessels

expanded on the air cells, and is changed from a dark to a florid

color: it is then returned back to the left ventricle, by the pulmonary

veins, and is propelled over the rest of the body, where it is again

changed (by the abstraction of certain properties) to the dark color

peculiar to venous blood: the blood is lastly conveyed by the veins

to the right side of the heart from whence it set out, having passed

through two circles.

The blood thus prepared by the lungs for circulation, passes in

different quantities to different parts of the body, according to

their activity, and has various fluids formed from it, which are

called secreted fluids, as gastric juice, milk, bile, &c. The parts

of the body forming many of these fluids, are very peculiar in their

structure, and are called _glands_. They consist in an arrangement of

vessels, endowed with a mode of action, with which we are unacquainted,

by which the component parts of the blood are disposed to enter into

new combinations, and to form compounds differing from the blood

itself. Thus the vessels are arranged on the inside of the stomach, in

such a way, as by their action to form gastric juice from the blood; on

the same principle, milk is produced from the blood which circulates

in the breast, or bile in the liver. As gastric juice, milk, and bile,

differ very much from each other in their properties, we must infer,

that there is a considerable variety in the action, by which these

vessels form these fluids from the blood; and this is necessarily

connected with a variety in arrangement, which is the case in all the

glands of the body. In one gland, for example, the blood-vessels form a

minute net-work; in another, are convoluted at their extremities; in a

third, a large branch suddenly divides into a number of small branches,

like the hairs of a painter’s brush; in a fourth, they are disposed in

an arborescent form, each gland differing from every other in the mode

of distribution of its blood-vessels, and forming different products

from the blood.

The substances formed by many of the glands of the body, are applied

to useful purposes, within or without the body. An instance of the

former we have in the bile formed by the liver, or the gastric juice

formed by the stomach; and of the latter, in the milk.--Other secreted

fluids are rejected as excrementitious: the best example of this is

the urine formed by the kidneys. This gland separates from the blood

a great variety of substances, which might otherwise prove noxious by

circulating along with it; many of these have occasionally very curious

chemical properties, and under a certain state of the body, the altered

secretion of this organ is very remarkable, in as far as it produces

a large quantity of a familiar substance, which in this instance is

composed within the body. In the disease called diabetes, for example,

a patient sometimes makes four or five gallons of urine in the 24

hours, in which is dissolved a considerable quantity of matter, like

common sugar or treacle, probably to the amount of two or three pounds.

Besides these fluids formed from the blood, each by an appropriate

glandular apparatus, there are watery fluids constantly secreted in

various parts of the body; and, that these may not accumulate, or

remain after they have performed their office, it is necessary for the

body to be furnished with vessels, whose powers of removal may keep

pace with the deposition of these fluids. This introduces the system

of vessels called _absorbents_, which are distinct in their office

and nature from the blood-vessels, and are widely diffused over the

whole body. In every part of the body a limpid fluid is thrown out for

the purpose of easy motion, moistening the cellular membrane, which

connects the various parts of the body to each other, and lubricating

the contents of all the cavities of the body; this fluid is thrown out

in the form of vapor by the exhalents, which belong to the arterial

system, whilst the lymphatic absorbent vessels, by their action,

remove what is not convenient for the function of the part; and these

two actions, of deposition, by the exhalents, and absorption, by the

lymphatics, go on during health, so nicely balanced, that when we open

into any of the great cavities of the body, as the belly or chest,

the quantity of fluid we find is extremely small. When, however, the

balance between these two orders of vessels is destroyed, when the

exhalents throw out more fluid than usual, and the lymphatics only

absorb their natural quantity; or the exhalents deposit their natural

quantity, whilst the lymphatics absorb less than natural, accumulation

of water in the cellular membrane, or great cavities of the body, takes

place, and produces dropsies.

There is another set of vessels, which have been already mentioned,

a part of the same system of absorbents, which from their office of

absorbing a white fluid, the chyle, have been denominated lacteals;

these arise from the inner surface of the intestines, in great numbers,

and convey the chyle into the general mass of blood.--Whilst the

minute beginnings of the lacteal vessels, from the internal surface

of the intestines, is a matter of ocular demonstration, we have only

presumptive proof of the origin of the lymphatics, which make the

greatest part of the absorbent system. We have, however, good grounds

for concluding, that they arise from every external and internal

surface of the body. We find, for example, that certain remedies, as

mercurial ointment, or turpentine, rubbed on the skin of any part of

the body, produce effects on distant parts; the mercury by removing

affections of various parts of the body, the turpentine increasing

the flow of urine, and giving it a peculiar odor: these effects are

explained by presuming the absorption of these substances, by the

lymphatics, arising from the surface of the skin. We have further proof

of this from the occasional absorption of watery fluids, under peculiar

circumstances. Sailors at sea, in want of fresh water, have quenched

their thirst by dipping their clothes in salt water, and applying them

to the surface of the body, from which only the elementary part was

absorbed by these vessels. A jockey, after reducing himself to a great

degree has become in a short time too heavy to ride his match, merely

by drinking a glass of wine, which had stimulated the absorbents of

the skin to take up a large quantity of aqueous matter from the air.

Or a person gibbeted alive, has been observed to make a considerable

quantity of urine as long as he lived, without any liquid being taken

by the mouth. These are all considered as evidences that the lymphatic

absorbent vessels arise from every external surface of the skin, and

are capable of taking up substances applied to them.

We find next that water accumulated in the large cavities of the chest

or abdomen, or underneath the skin in the cellular membrane, of every

part of the body, is occasionally removed from these situations, by

remedies which have the power of increasing the action of the absorbent

vessels. We hence conclude, that these vessels arise from every

internal part, and are, in short, widely diffused over the whole body,

though their beginnings are too minute to be detected by any mode of

examination with which we are acquainted.

The absorbent vessels, from whatever part they arise, terminate in the

blood-vessels, principally by one vessel or trunk, which is called the

_thoracic duct_. This commences in the cavity of the abdomen, passes

through the chest on the right side of the spine, and, at length,

enters a large vein situated on the left side of the neck. Through

this vessel, besides the fluids taken up in various parts of the body,

the whole of the nourishment from digested aliment passes into the

blood; it may therefore be said to be the most important vessel in the

body,[196] and it is situated in one of the safest positions in the

body, so that an injury done to it is a very rare occurrence.

Thus the absorbent system is formed of two sets of vessels, having the

same structure, the same absorbing office, and the same termination,

but differing in the fluids they convey, and the parts of the body they

occupy. The one widely diffused over the whole body, and from their

office of usually absorbing limpid fluids, called lymphatics; the other

arising only from the intestines, and denominated lacteals, from the

milky whiteness of the chyle they absorb.

Thus far the absorbent vessels have been described, as employed in

taking up fluids only. The action of the absorbent system, however,

is not considered as confined to the fluid parts of the body; there

are a variety of instances, in which the most solid parts appear to be

removed by the absorbents. Thus when a tooth is extracted, or drops out

in old age, its bony socket is removed by the action of the absorbents.

The pressure of a pulsating tumor, called aneurism, against the ribs,

or thigh bone, has produced their removal in the same way. These are

considered as instances of solid matter being removed by the absorbent

vessels, from internal parts of the body, without any external opening.

It is, however, a matter of doubt, which we cannot at present discuss,

whether a bone is broken down by the absorbents themselves, so as to

be removed in small particles; or whether, as is more probable, its

presence or irritation (as an extraneous body) produces the secretion

of a fluid, similar in its properties to the gastric juice, by which

it is first reduced into minute particles, or entirely dissolved, so as

thus to enter the absorbent vessels.

Another important part of the office of these vessels, is to

model the shape of the body, and to concur with the action of the

blood-vessels in regulating its growth. For the human body does

not, like a marble statue, constantly contain the same identical

particles in its composition. As the stream of a river is formed of

a constant succession of aqueous particles, sometimes increasing,

sometimes diminishing its natural bulk; so the human body is constantly

undergoing an imperceptible change of parts. The absorbents, by their

action, remove exhausted particles, whilst the arteries form from the

blood an adequate supply of new parts. When these two powers are equal,

the body continues of the same bulk; when from disease or contingent

circumstances, the one or the other predominates, the body increases in

growth, becomes corpulent, or emaciated.

Thus we have seen a variety of organs necessary to carry on the

functions of perfect animals: these, however, are inert, and incapable

of motion in themselves. Hence a _nervous system_ becomes requisite,

which may excite and influence the whole. We find in man, and

quadrupeds generally, the nervous system placed principally in the

brain and spinal marrow; from these sources, the nerves are distributed

like white cords, and pass in various proportions to the different

parts of the body, conveying the excitements of the brain.

One of the most important excitements conveyed from the brain, through

the medium of the nerves, is volition; by this means the muscles become

obedient to the will, and perform the voluntary actions of animals.

If, for instance, I wish to take up a pen, I exert my volition towards

the action, and the consequence of this is, that the muscles employed

in the action, are stimulated to contract, from a peculiar excitement

being conveyed to them from the brain, through the medium of the

nerves. We are totally ignorant, however, of the state of the brain,

whilst giving out the excitement, or the change which takes place in

the nerves whilst conveying it. We know, however, that the brain may

be rendered incapable of giving rise to the excitement, and it may be

arrested in its progress down the nerves by artificial means. If a

ligature be applied upon a nerve by tying a piece of thread round it,

the nerve is rendered incapable of transmitting the excitement, so as

to produce motion in muscles. The same state is frequently produced in

the brain and nerves, by the disease called palsy, or by fractures of

the skull. There are also various excitements passing from the brain

to the vital organs of the body, whose actions are not regulated by

the will, and are therefore called involuntary, or automatic actions,

as circulation, parturition, &c. Thus if a person have ever so strong

a desire, he cannot make his heart beat more frequently; nor can he

prevent it from beating more frequently, if any one should put him in

bodily fear; although the heart is formed of muscular flesh, similar to

the muscles, which he can command in his arm. The reason of this is,

that the nerves of the heart cannot convey the influence of volition;

for the wisest reasons the heart acts without it.

It is also necessary for various influences to be communicated from

external objects to the brain, to keep up a correspondence between

animals, and the material world around them, and to communicate

those impressions from which the brain is afterwards to carry on its

functions. As the parts formed for this purpose differ from ordinary

parts of the body, in having a larger share of nervous influence given

to them, they have been called the _organs of sense_, which in an

anatomical point of view, may be said to be five in number, the eye,

the ear, the tongue, the nose, and the skin.

In the _eye_, we discover a most accurate optical instrument, adapted

to converge the rays of light at its posterior part. It is composed of

a spherical box, containing transparent media of different densities,

by which the rays of light are conveyed to a point, so as to impress

a minute image of the visible appearance of external objects upon

the retina or expansion of the optic nerve, by which the impression

is conveyed to the brain, so as to bring us acquainted with external

objects.

The _ear_ is formed to receive impressions from bodies in a state of

vibration, which are conveyed to the brain by an apparatus composed of

various substances, and eminently calculated to transmit the slightest

tremors. The vibrations of the air, for instance, first strike the drum

of the ear; are thence communicated to a delicate chain composed of

four minute bones. By these the vibration is increased, and transmitted

to a fluid, contained in several small winding canals, in which the

delicate filaments of the nerves of hearing are arranged, so as to

transmit the impressions they receive from the surrounding fluids,

and produce in the brain the perception of sound; these two senses,

by the infinitely varied modification of their impressions, convey a

prodigious supply of materials for the action of the mind.

The organ of _touch_ is next in point of importance; it has its seat

in the extremities of the nerves distributed over the skin, and is the

only sense which belongs to every class of animals. This organ gives

rise to sensations, which have no natural alliance with each other.

By this sense we compare different degrees of temperature with each

other; from this we derive our idea of distance between bodies; of

their tangible figure, of their roughness, smoothness, hardness, and

other qualities, from the relative position with respect to ourselves,

or the degree or kind of resistance they offer. And, when man has

been deprived of his communication with many external objects, by the

loss of vision, we find the organ of touch gradually encroaching upon

the function of the eye, and from attention to its finer impressions,

becoming, through the education of necessity, a much more extensive

source of information. As an instance of this, I may adduce Mr. Gough,

who can accurately distinguish the color and character of flowers, by

the nice sense of touch possessed by the tip of the tongue.

The other senses may be said to be of less importance. The _nose_

affords a passage for the air to the lungs, and is impressed by the

odorous particles of bodies diffused through it, and, whilst it thus

occasionally administers to our gratification, it gives us notice of

the presence of those aeriform fluids which are noxious to respiration.

Like the organ of _taste_, which is impressed by sapid bodies, it has

a peculiar sympathy with the stomach; thus the taste, or smell, of any

disagreeable substance, very commonly excites sickness and vomiting.

Thus each of the organs of sense are formed in a peculiar manner, and

are supplied with nerves of a peculiar structure, which are capable

of being excited by certain impressions only, so as to give rise to

sensation. The odorous particles of bodies, for instance, if applied to

the nerves of the nose, excite an impression, which, when conveyed to

the brain, gives rise to the perception of smell; but, every one knows

that they produce no such effect when applied to the nerves of the

skin. In the same way, the rays of light applied to the nerves of the

eye produce vision; but, no such effect takes place when they impinge

upon the tongue.--Each of the organs of sense then possess a peculiar

modification of nerves, which are excited by appropriate impressions.

By these organs we become acquainted with what passes around us; but

the nervous system gives us notice of many changes which take place

within our bodies. Internal pains point out to us the presence and

situation of diseases; and the disagreeable sensations of hunger,

thirst, and fatigue, incline us to give refreshment and repose to the

body. It is also by means of the nervous system, that we experience the

passions and emotions of the mind.

There are some animals so simple in their structure, that neither

brain, nor organs of sense have been detected; yet they are endowed

with motion, and are capable of selecting and swallowing their

food, and expelling their excrement; and as these acts appear to be

voluntary, we must conclude, that they possess nervous matter, though

it be so interwoven with the rest of their structure that we cannot

exhibit or detect it.

All these different structures which have been described as entering

into the formation of a perfect animal, are soft and flexible in

themselves, and, in order to the right performance of their functions,

require the support of a substance of considerable firmness, which

may preserve them in their relative situations, and give a general

shape to the body. For this purpose, _bones_ are formed in the higher

orders of animals. They consist of a certain portion of animal matter,

on which their powers of life depend, mixed with a portion of earthy

matter, which gives them a degree of solidity. The firmest substance

in the body, composed entirely of animal matter, is cartilage, which

possesses, however, too little solidity for the support of animals of

considerable size, living in so rare a medium as air. Hence it happens

that when the earthy part is, by disease, abstracted from the bones,

they become bent and deformed by the weight of the body, or the action

of its moving powers. In fishes, however, who inhabit a denser medium,

cartilage becomes a convenient structure, being sufficiently firm

for their support, and, from its lightness, better suited to their

condition.

Had the osseous system been merely intended to give shape to animals,

and preserve the relative position of their parts, it might, for any

useful purpose, have been as well formed of one piece; and accordingly,

when almost all the bones of the body have been anchylosed, or

immoveably united to each other by disease, the functions of life have

gone on uniformly to an advanced age. There is a remarkable skeleton

of this kind preserved at Trinity College, Dublin; where all the large

bones of the body are immoveably united together, except the lower jaw,

and the joints of the fingers; every joint in the body was immoveable,

and yet this person lived to an old age. In order, however, that

animals may enjoy a power of changing their situation, the osseous

system has been composed of a variety of pieces, and an apparatus added

by which this may be easily effected. This is accomplished by adapting

the ends of bones to each other so as to form joints, which vary in

different parts of the body according to the motion of the part, some

being formed for strength, others for extent and variety of motion; the

two being incompatible, and never found in the same joint.

In the formation of a joint, however, it appears that two surfaces

of bone would move with considerable attrition upon each other, not

being capable of a sufficient degree of smoothness; it is therefore

necessary, in order to diminish attrition, that a substance be

interposed having a high degree of polish; this is supplied by

cartilage, with which the ends of all bones, performing motion, are

covered; and as animals, both from the common occurrences of life, and

from accident, are liable to considerable shocks, in order to guard

the system, as much as possible, against injury from these sources,

cartilages are endowed with a considerable degree of elasticity, and

thus by their reaction are capable of evading certain degrees of

violence.

The smoothness of cartilage, however, only prevents attrition to a

certain degree; that joints therefore may move with all possible ease

and freedom, a fluid is interposed called _sinovia_. This is separated

from the blood, by the vessels distributed to the inner surface of the

joint, and is the most slippery of all fluids.

In order that bones may not be separated from each other, but preserve

their relative situations, with a certain capacity of motion, it is

requisite that they should be joined together; this is done by the

ligaments surrounding a joint, which are of two kinds. The one adapted

to the firm junction of the bones with each other, upon which the

strength of the joint depends; the other loosely attached round the

ends of contiguous bones, to secrete sinovia, and retain it in its

proper situation; and hence called capsular or purse-like ligament.

This kind of structure, endowed with a power of secreting sinovia, is

not confined to the joints alone; for in many parts of the body, where

muscles during their action rub on bones, or tendon on tendon, small

bags are formed for supplying sinovia, which are called bursæ mucosæ.

As all these parts subservient to motion are inert in themselves,

that animals may enjoy the means of changing their situations and

attitudes, a power must be applied to the bones for this purpose, which

is supplied by muscular action. Thus we find the bones clothed with

_muscles_, which give, in a great measure, the external shape to the

body, and act in considerable numbers on the joints, particularly those

which possess much motion.

All animals have a muscular structure entering into their composition,

with some variety in its appearance. Muscles are generally fibrous

to the eye, and in Man and Quadrupeds are of a red color; in some

animals, however, these circumstances are not at all obvious. Thus in

many fishes, the muscles are white, and put on a flaky appearance;

whilst in the fresh water Polypus, which possesses a great degree of

contractile power, no fibres can be seen. So that it is not necessary

that these properties should be obvious in the muscles of all animals.

Thus no person has ever seen the fibres in the muscles of a Flea, yet

no animal can exert greater muscular power. In the same way, many parts

of the body possess a contractile power, which have no apparent fibrous

structure; the best example of this, is the skin of the scrotum. The

redness of a muscle, in fact, depends in a great measure on the degree

of exertion it undergoes; thus when a limb becomes motionless from

palsy, the muscles uniformly become pale.--The function of a muscle

consists in its contracting or shortening itself, in consequence of

the application of certain stimuli or excitements; the effect of this

contraction is, that the different bones to which the muscles are

attached are moved in various directions. Thus (to give an example) a

muscle affixed to two contiguous bones, by shortening itself, brings

those points to which it is affixed nearer to each other; and, from

this mechanism, arise all the motions of the body. The greatest part

of the muscles which put the limbs in motion by their contractions,

are said to act under the excitement of volition, or, in other words,

are under the control and influence of the will, and are therefore

called voluntary muscles. There are many muscles, however, which are

not excited by volition, and are therefore called involuntary. As these

are directed by influences, and perform the actions on which life

immediately depends, they, for obvious reasons, are not only put beyond

the powers of the will, but are enabled to carry on their contractions

and motions without interruption or fatigue, entirely independent of

its direction or our consciousness. In this manner the heart performs

the circulation of the blood, and the stomach and intestines give the

requisite motion to the food.--There are many other excitements which

produce contraction in muscles, such as the passions and emotions of

the mind, and various mechanical and chemical stimuli. Some of them

occasionally excite the voluntary muscles of the body to a degree

of action, over which volition has no control. Thus a person in an

ordinary state of mind, can walk more or less quietly as suits his

convenience; but it occasionally happens, we shall say in the field of

battle, that the passion of fear is excited; this excitement frequently

disregards the power of the will, and strongly excites the muscles

employed in running away.[197]

In most animals, there is connected with the muscles another kind of

structure called _tendon_, which consists in a white substance very

different from muscles, but having a fibrous structure. Although

tendons are not necessary to the action of muscles, yet there are

several advantages derived from them; they occupy much less room than

muscles, and can be placed in greater numbers around the joints, so

as to preserve the beauty and uniformity of the limbs. They may be

considered as living cords, joining the muscle to the bone on which it

is to act, and, being more scantily supplied with blood than muscles,

make a smaller quantity of blood necessary to the system, which is

certainly a convenience. Although the different parts of the body

vary very much in their functions and degree of motion; yet, it is

convenient, that they should be all united together by a substance of

considerable elasticity. This is done by the interposition of _cellular

membrane_, which is the general connecting medium throughout the body,

attaching each organ to its neighbor, but allowing sufficient play for

the performance of its function.

It is in the cellular membrane of different parts of the body that fat

is deposited; and from the seeming caprice of nature, in overloading

some animals, and entirely denying it to others, its use has been

thought inconsiderable in the system. When, however, we remark, that

fat is taken up in some diseases where the appetite is impaired; and

that torpid animals, before hibernation, have a large quantity of it

accumulated, and come out of that state quite emaciated: and that

bees, who have no fat in their bodies, lay up a stock of food, having

the same chemical properties, against their hibernating season; it

appears very probable, that one use of fat is to form a reservoir of

nutriment, which supplies the wants of an animal when food is not

introduced by the stomach.

If we add the _skin_ to the cellular membrane, we may say, without

these the beauty and symmetry of the exterior would have been much

diminished. We should have seen the raw muscles in all their actions,

and the naked nerves exposed to the air and to injury. There would have

existed deep fissures between the muscles, cavities in almost every

part, and the body would have presented the sad appearance it now does

in consumption.[198] But the cellular substance in some places only

separates one part from another, or affords a slippery surface for one

muscle to slide over the other: in others forming membranes or fascia

to hide, to bind down and strengthen different organs; while in others

admitting into its cells an oily substance, becomes fat, and fills up

all the interstices, rounds off all prominences, softens acute lines,

and gives a graceful softness and contour to the whole. And the skin

enveloping in a close case, keeps all compact, and hides from the eye

whatever might be offensive: while, at the same time the cutis or

true skin serves for a surface for the nerves and exhalent vessels to

terminate, the cuticle or scarf skin defends them from injury, and

moderates their excessive sensibility.

As all animals are to live in media where the heat varies, it was

necessary either to form them in such a way, that their functions

should not be affected by varieties in temperature, or that they should

be enabled to keep up the heat of their bodies at a regular point.

Animals have been endowed with the latter power, and can accordingly

maintain their heat, whether exposed to a high or low degree of

temperature, with some exception as to the degree in the lower orders

of animals, in some of which the temperature varies with that of the

medium in which they are placed. This is the case with the Frog.--This

animal, when placed in warm water, has the temperature of its body

raised several degrees, and, on the other hand, may be reduced to

the freezing point, without producing death. The heat of the human

body, however, is little changed, whether it be exposed to intense

cold, or much above the heat of boiling water. In the experiments

made in heated rooms by Dr. Fordyce, and Sir Charles Blagden, these

gentlemen remained several minutes in the heat of 260 degrees, nearly

50 degrees more than boiling water. At this heat a beefsteak and eggs

were cooked near the stove, and yet the heated air produced no bad

effect upon their bodies: it raised the temperature of their bodies

only a few degrees.--The lungs are the chief agents by which heat is

introduced into animal bodies. By their means, the blood is exposed to

the air, and consumes its oxygenous part, which contains the principle

of heat in a combined state. This, during circulation, is evolved by

the minute blood vessels, so as to become sensible on every part of

the body: and it is an important fact, that the quantity of oxygen

consumed is greater in cold than warm weather; by this wise provision,

in proportion as the heat is more quickly carried off by the coldness

of the surrounding medium, the animal receives an increased internal

supply. Many experiments have been instituted to ascertain the quantity

of oxygen consumed in a given time by ordinary respiration, and,

according to the best calculations, it appears that the consumption

amounts to about 33½ ounces troy weight, in 24 hours; and it has been

computed by philosophers, that the quantity of heat, which the oxygen

consumes and will supply to the body, is nearly equal to that given out

by a common candle.[199] I have thus attempted to give a short view of

the different structures and functions of the body, and have briefly

pointed out some of their varieties in the different classes of animals.

This corporeal system, which by its uniform and harmonious action

contributes so essentially and largely to our terrestrial enjoyment,

exhibits an astonishing display of the infinite wisdom, almighty power,

and boundless goodness of its glorious Creator. Galen, an ancient Pagan

physician, on contemplating the different parts of the human body, and

the disposition of them, fell on his knees in humble adoration of the

wisdom with which the whole is contrived; and was excited to challenge

any one, after a hundred years’ study, to tell how the least fiber or

particle could have been more commodiously placed, either for use or

beauty. His seventeen books on the subject are like so many hymns of

praise to the almighty and all-wise God, the Creator. Lactantius calls

his writings on the body of man, a marvellous comment on his creation,

and Galen himself managed the subject as a full demonstration of a

Deity which every man carries about with him.

But what is still more deserving of our attention is the _soul_ of man:

for if the external structure be so admirable a piece of mechanism,

what shall we say of the immaterial and intellectual spirit resident

in it? This noble, constituent, essential part of man, is yet a more

astonishing production of infinite skill and power. Elihu says, “The

Spirit of God hath made me, and the breath of the Almighty hath given

me life. There is a spirit in man, and the inspiration of the Almighty

giveth them understanding.” God, by his creating energy, called all

things out of nothing, but there was neither order, light, nor motion,

till the Divine Spirit moved on the lifeless chaos; so the same

all-wise and powerful Architect formed of clay the wonderful fabric

of man’s body, which remained without life and action, till the Holy

Spirit infused a vital spirit into him, thereby enduing him with sense,

motion, understanding, will, and active powers. This soul, therefore,

became a living principle of intelligence, consciousness, and activity,

in man.

The great Creator said, “Let us make man in _our image_, after _our

likeness_.” Now, as the Divine Being is infinite, he is neither

limited by parts, nor definable by passions: therefore he can have

no _corporeal image_ after which he formed the body of man. The

_image_ and _likeness_ in which he was created must necessarily be

intellectual: his soul must have been formed after the nature and

perfections of God. The Creator was now producing a spirit, formed

after himself. He is the fountain whence it issued; hence the stream

must resemble the spring which produced it.

The most perfect description of God, given to us in the Scripture,

is that by our Saviour:--“God is a Spirit.” It has been observed by

expositors, that this assertion is no where else to be found in the

sacred Writings. That passage, “Now the Lord is that Spirit,” sounds

something like it, but in meaning is different. The word _God_ here

is not to be understood personally, either for the Father, or the

Son, or the Holy Ghost, alone, but essentially for the Divine Nature,

which each of these glorious Persons possesses. The Divine Nature is

_spirit_. This shows, that, according to the popular and common use of

the word, he is a Being entirely separated from matter or body, in all

its properties and affections; that he is a pure mind, and possessed of

the most excellent powers and perfections, which belong to spiritual

beings.

It is difficult, for persons of a low understanding, who are

unaccustomed to abstract reflections, and who have imbibed their

knowledge by means of the external senses, employed on material

objects, to raise their minds to the contemplation of the existence

of immaterial, invisible beings. But that there really are such, and

particularly that God is such, admits of the clearest proof, and will

not be called in question by any who on rational grounds acknowledge

his existence. It is usually granted, that it is much more easy to say

what a spirit is not, than to define what it is. It is not in the power

of the wisest and most knowing of men, to declare its nature. Nay, who

can explain what the consistence of any piece of matter is, which we

every day see and touch!

But as, notwithstanding our ignorance of the essence of material

objects, we are not only sure of their existence, but also know many

of their properties; so in like manner, though we are ignorant of the

nature of spirits, yet from their manifest operations and effects, we

are both convinced that such beings exist, and have some notion of

several of their faculties and powers.

The powers and capacities that we observe in all the operations and

works of God, are utterly inconsistent with the properties we discern

in matter. In the works of creation we perceive evident proofs of

thought, intention, contrivance, and design; which powers, we are sure,

having no affinity with solidity, figure, and a capacity of being moved

by the impulse of another, cannot arise from the composition or mixture

of any of the known properties of matter. Not only the existence, but

many of the perfections of God, may be discerned in various parts of

the universe.

In short, we can say nothing higher of God, than that he is a Spirit.

This notion leads us to conceive of him as a most perfect Being, and

to reject concerning him whatever would argue any imperfection. It

leads us to believe him to be perfectly immaterial, free from all the

imperfections of matter, and from all the infirmities of corporeal

creatures. But though _spirit_ signifies a being of higher rank than

body or matter, yet the word is too low to express the essence of God,

any otherwise than analogically, or metaphorically. He is infinitely

more excellent than the highest created spirits, being eternal, and

immutable. But some may inquire, if God be such a Spirit, how is it

that in Scripture we read of his having bodily members, and natural

affections, like men; such as head, eyes, ears, mouth, hands, and feet;

and the affections, or passions, of anger, grief, love, joy, &c? these

are ascribed to him, or rather assumed by him. I answer; this is done

in condescension to our narrow capacities; for if God should speak

to us of himself, as he is in himself, our understandings could not

comprehend him. As the inconceivable glories of the world to come, are

explained to us by the honors and pleasures of this life; so the nature

of God, by a gracious condescension to our weakness, is signified to

us by a likeness to our own. By human members being ascribed to God,

are implied the moral excellencies of his spiritual nature, or rather

his operations, which are more sensible to us than his invisible

nature. His eyes are emblems of his knowledge, wisdom, omniscience, and

providence. His face indicates his favor, and sometimes is expressive

of his displeasure, because both these appear in the countenance of

a man. His mouth is the symbol of the revelation of his will. His

hand, or arm, is indicative of the less or greater exercises of his

power.--Such a _Spirit_ is the Creator of man, whom he made in his

_image_ or _likeness_.

Whoever reflects with attention on the human soul, may easily

perceive it to be of a nature entirely different from the body. Being

immaterial, it is not compounded of material principles, nor consists

of innumerable parts which may be separated from each other; neither

is it capable of solidity, figure, extension, and other properties

of matter; but is a simple, uncompounded substance, though possessed

of various and distinct powers; and therefore is neither visible nor

divisible, nor has it any dimensions or shape.

The soul has a power of _thought_, with which mere matter can never

be endued. If it pass through all the changes, and assume all the

shapes of which it is capable, thought will never be the result. It may

be differently modified, framed, and disposed, but cannot think. “I

find in me something that _thinks_,” says a celebrated author, “which

neither earth, water, air, fire, nor any mixture of them, can possibly

do. Something which sees, hears, smells, tastes, and feels, all which

are so many modes of thinking.” Thought is the privilege of immaterial

beings.[200]

This inward principle is capable not only of thinking, but of love,

desire, hope, joy; hatred, fear, sorrow, anger, and a whole train of

inward emotions, which are commonly called _passions_ or _affections_.

A something apprehended to be good in itself, or calculated to be

beneficial to us, is the object of love. If that good be absent,

it excites desire: if there be a probability of obtaining it, that

produces hope; and the possession of the desired object yields delight

and joy. Evil, whether real, or imaginary only, is the object of

dislike and aversion. If there be any probability of this evil coming

in contact with us, it causes fear; and if it unavoidably come upon us,

it produces sorrow or anger. These passions or affections seem to be

the only spring of action in the soul.

The soul has received from God a principle of motion, whereby

it governs at pleasure every part of the body, and directs its

operations: only with this exception, that all the vital motions,

which are absolutely necessary for the continuance of animal life,

are involuntarily going on, whether we advert to them or not; which

is a marvellous instance of the wisdom and goodness of God. With the

exception of these, I direct the motion of my whole body. By a single

act of my will, I put my head, eyes, hands, or any part into motion:

although the manner of doing this I do not comprehend. Every one feels

that he has an inherent power to move this or that part of his body or

not, and to give it a direction this way or the contrary, just as he

pleases. I can, as I choose, open or shut my eyes, speak or be silent,

rise up or sit down, stretch out my hand or draw it in, and use any of

my limbs according to my pleasure, as well as my whole body. Matter may

be moved, but it can never move itself.

The soul is free in its operations; it possesses this property, which

is capable of being exerted with regard to all its faculties, as well

as all the motions of the body. It is a power of self-determination,

which, though not affecting all our thoughts and imaginations, yet

extends to our words and actions in general, with but few exceptions.

I am certain, that I am free to speak or not to speak, to act or not

to act, to do this or to do the contrary, as I am of my own existence.

I have not only what is termed a _liberty of contradiction_, but what

is termed a _liberty of contrariety_, a power to act one way, or the

contrary: to deny this would be to contradict the uniform experience

of all human kind. The soul is not necessitated to judge or act by any

bodily impulse. Let things appear as they may to the senses, the soul

can suspend its judgment, till it has examined and considered them more

thoroughly. Let the appetites and inclinations of the body strongly

urge their own gratification, the soul can refuse their solicitations,

and maturely weigh what the consequences would be. Let all the

allurements of sensible objects, the assurance of sensual enjoyments,

or the influence of custom and example, try to corrupt the integrity

of the soul, and lead it astray from the paths of peace and purity;

unless it consent, the attempts will prove ineffectual. We can reason,

discourse, study, contrive, choose, and refuse with discretion; begin

a work, and cease again at pleasure. We can reflect on what we have

done, and either rejoice and delight in it, or be ashamed and grieved

for it. We distinguish truth from error, moral good and evil; we fear

punishment on having committed evil, and hope for reward on having done

well. And, through the grace of God assisting us, we have a power to

embrace and resolve to do good, as well as evil. We are free to choose

whom we will serve, and, if we determine in favor of the better part,

to continue therein.

_Conscience_ is not a faculty of the soul distinct from the

understanding, memory, will, and affections, but that power by which we

are conscious of our own state, reflect on our actions, and pronounce

them either good or evil. This supposes, that we are acquainted with

the law of God, either natural or written, which is the rule of our

duty. The name is derived from the Latin word _conscientia_, into which

the Greek word συνειδησις is exactly translated. Both these words for

conscience, signify, that the mind is possessed of a consciousness of

the actions and thoughts of the man, and passes a judgment on them,

according to some rule. The Jews have no proper word in their language

for conscience, and therefore use the term _heart_; which is also

used in the New Testament. Conscience is the journal or diary of the

actions of man. Its office is, 1. To call, urge, and excite us to duty.

2. To testify and bear witness either for or against us, according

as we perform or neglect our duty. 3. Either to excuse or acquit, or

accuse and condemn us, on the evidence it gives of the moral nature

and quality of our actions: if they be conformable to the Divine rule,

as to matter and manner, it acquits us; if they be contrary to it,

conscience accuses, condemns, and passes sentence upon us. 4. And if

its sentence be true and just, conformable to rule, it is ratified by

God the Supreme Judge, whose deputy and vicegerent it is in the breast

of every man.