I tried to breed from the male quagga an_An Examination of Weismannism

seven-eighths Arabian blood, and which had never been bred from;

the result was the production of a female hybrid, now five years

old, and bearing, both in her form and in her colour, very decided

indications of her mixed origin. I subsequently parted with the

seven-eighths Arabian mare to Sir Gore Ouseley, who has bred from her

by a very fine black Arabian horse. I yesterday morning examined the

produce, namely, a two-year-old filly and a year-old colt. They have

the character of the Arabian breed as decidedly as can be expected,

where fifteen-sixteenths of the blood are Arabian; and they are fine

specimens of that breed; but both in their colour and in the hair of

their manes they have a striking resemblance to the quagga. Their

colour is bay, marked more or less like the quagga in a darker tint.

Both are distinguished by the dark line along the ridge of the back,

the dark stripes across the fore-hand, and the dark bars across the

back part of the legs[75].

Lord Morton then names sundry further correspondences. Dr. Wollaston,

at that time President of the Royal Society, who had seen the animals,

testified to the correctness of his description, and, as shown by his

remarks, entertained no doubt about the alleged facts. But good reason

for doubt may be assigned. There naturally arises the question—How

does it happen that parallel results are not observed in other cases?

If in any progeny certain traits not belonging to the sire, but

belonging to a sire of preceding progeny, are reproduced, how is it

that such anomalously-inherited traits are not observed in domestic

animals, and indeed in mankind? How is it that the children of a

widow by a second husband do not bear traceable resemblances of the

first husband? To these questions nothing like satisfactory replies

seem forthcoming; and, in the absence of replies, scepticism, if not

disbelief, may be held reasonable.

There is an explanation, however. Forty years ago I made acquaintance

with a fact which impressed me by its significant implications; and

has, for this reason I suppose, remained in my memory. It is set forth

in the _Journal of the Royal Agricultural Society_, vol. xiv. (1853),

pp. 214 et seq., and concerns certain results of crossing English

and French breeds of sheep. The writer of the translated paper, M.

Malingié-Nouel, Director of the Agricultural School of La Charmoise,

states that when the French breeds of sheep (in which were included

“the _mongrel_ Merinos”) were crossed with an English breed, “the

lambs present the following results. Most of them resemble the mother

more than the father; some show no trace of the father.” Joining the

admission respecting the mongrels with the facts subsequently stated,

it is tolerably clear that the cases in which the lambs bore no traces

of the father were cases in which the mother was of pure breed.

Speaking of the results of these crossings in the second generation

“having seventy-five per cent. of English blood,” M. Nouel says:—“The

lambs thrive, wear a beautiful appearance, and complete the joy of the

breeder.... No sooner are the lambs weaned than their strength, their

vigour, and their beauty begin to decay.... At last the constitution

gives way ... he remains stunted for life”: the constitution being thus

proved unstable or unadapted to the requirements. How, then, did M.

Nouel succeed in obtaining a desirable combination of a fine English

breed with the relatively poor French breeds?

He took an animal from “flocks originally sprung from a mixture of

the two distinct races that are established in these two provinces

[Berry and La Sologne],” and these he “united with animals of another

mixed breed, ... which blended the Tourangelle and native Merino blood

of” La Beauce and Touraine, and obtained a mixture of all four races

“without decided character, without fixity, ... but possessing the

advantage of being used to our climate and management.”

Putting one of these “mixed-blood ewes to a pure New-Kent ram ...

one obtains a lamb containing fifty-hundredths of the purest and

most ancient English blood, with twelve and a-half hundredths of

four different French races, which are individually lost in the

preponderance of English blood, and disappear almost entirely, leaving

the improving type in the ascendant.... All the lambs produced

strikingly resembled each other, and even Englishmen took them for

animals of their own country.”

M. Nouel goes on to remark that when this derived breed was bred with

itself, the marks of the French breeds were lost. “Some slight traces

could be detected by experts, but these soon disappeared.”

Thus we get proof that relatively pure constitutions predominate in

progeny over much mixed constitutions. The reason is not difficult

to see. Every organism tends to become adapted to its conditions

of life; and all the structures of a species, accustomed through

multitudinous generations to the climate, food, and various influences

of its locality, are moulded into harmonious co-operation favourable

to life in that locality: the result being that in the development

of each young individual, the tendencies conspire to produce the

fit organization. It is otherwise when the species is removed to a

habitat of different character, or when it is of mixed breed. In the

one case its organs, partially out of harmony with the requirements

of its new life, become partially out of harmony with one another;

since, while one influence, say of climate, is but little changed,

another influence, say of food, is much changed; and, consequently, the

perturbed relations of the organs interfere with their original stable

equilibrium. Still more in the other case is there a disturbance of

equilibrium. In a mongrel the constitution derived from each source

repeats itself as far as possible. Hence a conflict of tendencies

to evolve two structures more or less unlike. The tendencies do not

harmoniously conspire; but produce partially incongruous sets of

organs. And evidently where the breed is one in which there are united

the traits of various lines of ancestry, there results an organization

so full of small incongruities of structure and action, that it has

a much-diminished power of maintaining its balance; and while it

cannot withstand so well adverse influences, it cannot so well hold

its own in the offspring. Concerning parents of pure and mixed breeds

respectively, severally tending to reproduce their own structures in

progeny, we may therefore say, figuratively, that the house divided

against itself cannot withstand the house of which the members are in

concord.

Now if this is shown to be the case with breeds the purest of which

have been adapted to their habitats and modes of life during some

few hundred years only, what shall we say when the question is of a

breed which has had a constant mode of life in the same locality for

ten thousand years or more, like the quagga? In this the stability

of constitution must be such as no domestic animal can approach.

Relatively stable as may have been the constitutions of Lord Morton’s

horses, as compared with the constitutions of ordinary horses, yet,

since Arab horses, even in their native country, have probably in the

course of successive conquests and migrations of tribes become more

or less mixed, and since they have been subject to the conditions of

domestic life, differing much from the conditions of their original

wild life, and since the English breed has undergone the perturbing

effects of change from the climate and food of the East to the climate

and food of the West, the organizations of the horse and mare in

question could have had nothing like that perfect balance produced in

the quagga by a hundred centuries of harmonious co-operation. Hence the

result. And hence at the same time the interpretation of the fact that

analogous phenomena are not perceived among domestic animals, or among

ourselves; since both have relatively mixed, and generally extremely

mixed, constitutions, which, as we see in ourselves, have been made

generation after generation, not by the formation of a mean between two

parents, but by the jumbling of traits of the one with traits of the

other, until there exist no such conspiring tendencies among the parts

as cause repetition of combined details of structure in posterity.

Expectation that scepticism might be felt respecting this alleged

anomaly presented by the quagga-marked foal, had led me to think over

the matter; and I had reached this interpretation before sending to the

College of Surgeons Museum (being unable to go myself) to obtain the

particulars and refer to the records. When there was brought to me a

copy of the account as set forth in the “Philosophical Transactions,”

it was joined with the information that there existed an appended

account of pigs, in which a parallel fact had been observed. To my

immediate inquiry—“Was the male a wild pig?”—there came the reply:

“I did not observe.” Of course I forthwith obtained the volume, and

there found what I expected. It was contained in a paper communicated

by Dr. Wollaston from Daniel Giles, Esq., concerning his “sow and her

produce,” which said that

she was one of a well-known black and white breed of Mr. Western,

the Member for Essex. About ten years since I put her to a boar of

the wild breed, and of a deep chestnut colour, which I had just

received from Hatfield House, and which was soon afterwards drowned by

accident. The pigs produced (which were her first litter) partook in

appearance of both boar and sow, but in some the chestnut colour of

the boar strongly prevailed.

The sow was afterwards put to a boar of Mr. Western’s breed (the wild

boar having been long dead). The produce was a litter of pigs some

of which, we observed with much surprise, to be stained and clearly

marked with the chestnut colour which had prevailed in the former

litter.

Mr. Giles adds that in a second litter of pigs, the father of which

was of Mr. Western’s breed, he and his bailiff believe there was a

recurrence, in some, of the chestnut colour, but admits that their

“recollection is much less perfect than I wish it to be.” He also adds

that, in the course of many years’ experience, he had never known the

least appearance of the chestnut colour in Mr. Western’s breed.

What are the probabilities that these two anomalous results should have

arisen, under these exceptional conditions, as a matter of chance?

Evidently the probabilities against such a coincidence are enormous.

The testimony is in both cases so good that, even apart from the

coincidence, it would be unreasonable to reject it; but the coincidence

makes acceptance of it imperative. There is mutual verification, at the

same time that there is a joint interpretation yielded of the strange

phenomenon, and of its non-occurrence under ordinary circumstances.

And now, in the presence of these facts, what are we to say? Simply

that they are fatal to Weismann’s hypothesis. They show that there

is none of the alleged independence of the reproductive cells;

but that the two sets of cells are in close communion. They prove

that while the reproductive cells multiply and arrange themselves

during the evolution of the embryo, some of their germ-plasm passes

into the mass of somatic-cells constituting the parental body, and

becomes a permanent component of it. Further, they necessitate the

inference that this introduced germ-plasm, everywhere diffused, is

some of it included in the reproductive cells, subsequently formed.

And if we thus get a demonstration that the somewhat different units

of a foreign germ-plasm permeating the organism, permeate also the

subsequently-formed reproductive cells, and affect the structures of

the individuals arising from them, the implication is that the like

happens with those native units which have been made somewhat different

by modified functions: there must be a tendency to inheritance of

acquired characters.

My reply to this appeared in the April issue of the _Contemporary

Review_, as follows:—

_Influence on Progeny of a Previous Sire._

This is the last of the arguments which Mr. Spencer advances against

the position of Professor Weismann. Alluding to the case of Lord

Morton’s mare, he represents that the phenomenon which it serves so

well to illustrate—viz., the influence of a previous sire on the

progeny of another by the same dam—is hopelessly at variance with

the theory of germ-plasm. I cannot quite gather the explanation which

he would give of this phenomenon, further than that in some way or

another it betokens an immediate influence of the hereditary material

of the male on the body-tissues (“somatic cells”) of the female. And

this is the view which is taken of the phenomenon by the Lamarckians

in general. Yet, if we consider all that such an explanation involves,

we shall find that it is a highly complex explanation, for it involves

the following chain of hypotheses:—The first impregnation affects

many, if not all, the somatic tissues of the mother by the germinal

matter of the father; these tissues, in their turn, react on the

maturing ova; this action and reaction is such that when one of the

ova is afterwards fertilized by a different sire, the resulting

offspring more or less resemble the preceding sire. Unfortunately,

neither Weismann himself nor any of his followers, as far as I know,

has hitherto published an opinion on the subject; but I imagine that

his answer would be three-fold. First, he may question the fact.

Secondly, even admitting the fact, he may say it is much more easy

to explain it by supposing that the germ-plasm of the first sire has

in some way or another become partly commingled with that of the

immature ova, as well as with that of the mature one which it actually

fertilizes; and, if so, it would naturally assert its influence on the

progeny of a subsequent sire. Millions of spermatozoa must have been

playing around the ovaries after the first copulation, and only one

of them was needed to fertilize the mature ovum. It is not necessary

to suppose that some of the others succeeded in penetrating any of

the immature ova, while these were still embedded in the substance of

their ovaries. It may be that the life of “ids” Is not commensurate

with that of their containing spermatozoa. After the latter have

perished and disintegrated, their ids may escape in thousands of

millions, bathing in a dormant state the whole surfaces of both

ovaries. And, if so, it is conceivable that when subsequent ova

mature—i.e., come to the surface of their ovaries and rupture their

follicles—these dormant ids adhere to their porous walls, through

which they may pass. This may not seem a very probable explanation;

but, at any rate, it is a less improbable one than that on which the

Neo-Lamarckians would found an argument against the continuity of

germ-plasm. For,—

Thirdly, is it not literally inconceivable that this Neo-Lamarckian

explanation can be the true one? Can it be seriously contemplated that

there is any such mechanism as the explanation must needs assume?

If it is difficult to accept such a machinery as is supposed by

the theory of pangenesis, whereby every cell in the body casts off

“gemmules,” which are the carriers of heredity from their respective

tissues to the germinal elements, what are we to say of such a

machinery as the following:—A machinery which distributes through

the body of a female gemmules from the disintegrated spermatozoa of

her mate; which distributes them _selectively_, so that they shall

all eventually lodge in those tissue-cells of the female which

correspond, part for part, with the tissue-cells of the male from

which they were originally derived; which then insures that when a

gemmule has thus reached its appropriate cell in the female body, it

will thereupon modify the pre-existing gemmules in that cell, so that

when they are shed and go to form the germinal contents of future ova,

they endow the latter with the hereditary qualities of the male in

question?

Such, it seems to me, is a fair statement of the whole case up to

date. But I think it may be apposite now to publish the main results

of an inquiry on which I have been engaged for the last three years.

First as to the facts. The investigations have been pursued on

three different lines: (1) I raised discussions on the subject in

the principal breeders’ and fanciers’ journals of this country, and

also of America. (2) I entered into private correspondence with

contributors of the largest experience, and also with professional

and amateur breeders, fanciers, &c., who addressed me directly on the

subject. (3) I started experiments with the varieties which these

inquiries indicated as most likely to yield positive results. At

present nothing need be said with regard to these experiments, because

they are not sufficiently matured. But it is desirable to state the

general upshot of the correspondence.

The principal result is to show that the phenomenon is of much less

frequent occurrence than is generally supposed. Indeed, it is so

rare that I doubt whether it takes place in more than one or two per

cent. of cases. I must add, however, that nearly all my professional

correspondents would deem this an absurdly low estimate. Most of them

are quite persuaded that it is of frequent occurrence, many of them

regard it as a general rule, while some of them go so far as to make a

point of always putting a mare, a bitch, &c. to a good pedigree male

in her first season, so that her subsequent progenies may be benefited

by his influence, even though they be engendered by inferior sires.

But I am certain that these estimates must be largely discounted in

view of merely accidental resemblances, and still more on account of

the prevalent belief upon the subject, which, where unquestioningly

entertained, prevents anything like a critical estimate being formed.

But that the phenomenon does occur in some small percentage of cases

there can be no reasonable doubt—as a result, I mean, of analysing

the hundreds of cases which have now been submitted to me, especially

with regard to dogs. One thoroughly well observed case occurring

among pedigree animals is worth any number of slipshod statements,

when precedent belief, inefficient isolation, exaggeration of memory,

and so forth, have to be allowed for. On the present occasion space

does not admit of giving such special instances, so I must ask it to

be taken for granted that my evidence is enough to prove the fact

of a previous sire asserting his influence on a subsequent progeny,

although this fact is one of comparatively rare occurrence. It may

be added that I have failed to find any good evidence of its ever

occurring at all in the case of man. For although I have met with an

alleged instance of a white woman, who, after having borne children

to a negro husband, had a second family to a white one, in which some

negro characteristics appeared, I have not been able to meet with any

corroboration of this instance. I have made inquiries among medical

men in the Southern States of America, where in the days of slavery

it was frequently the custom that young negresses should bear their

first children to their masters, and their subsequent children to

negro husbands; but it never seems to have been observed, according

to my correspondents, that these subsequent children were other than

pure negroes. Such, however, was not the same case as the one above

mentioned, but a reciprocal case; and this may have made a difference.

If any reader should happen to know of another instance where a negro

was the first husband, I hope he will inform me as to the result.

It has hitherto puzzled me why the phenomenon in question, since it

does certainly occur in some cases, should occur so rarely as the

above inquiries prove. But I think that Mr. Spencer’s suggestion on

this point is a valuable one, as it seems to present an excellent

promise of solving the puzzle.

This suggestion, it will be remembered, is that when the first sire

is of a relatively stable and also of a markedly different ancestral

stock from the dam—e.g., of a different species, as in the case of

Lord Morton’s mare—there will be most likelihood of his impressing

his ancestral characters on the progeny of the second sire[76]. And,

as he remarks, it would indeed be an extraordinary coincidence if

both the well-authenticated cases given in the College of Surgeons

Catalogue should have conformed to his explanation by mere accident.

To which I may add that the supposition of such an accidental

coincidence would seem to be virtually excluded by the recent

occurrence of yet a _third_ case of exactly the same kind. This took

place in the Zoological Gardens, where a wild ass of one species was

the previous sire to a foal born of another species: the subsequent

sire was of the same species as the mother, and his foal, born a

few months ago, presented an unmistakable resemblance to the other

species. A brief account of the particulars is given by Mr. Tegetmeier

in the _Field_ for December 14, 1892.

So much, then, for the facts. As regards their interpretation, it

certainly seems to me that the one which I have supposed to be given

by Weismann is less difficult of acceptance than the one which is

given by the Lamarckians, as we have seen above. But it also seems

to me that the latter explanation is not the only one available

under the Lamarckian hypothesis. For, even under this hypothesis,

there is no need to assume that the influence of the first sire

is exerted on all the somatic tissues of the mother, and that

these again reflect this influence on the ovum which is afterwards

fertilized by the second sire. A mechanism that could effect all

this may well be deemed impossible. But a much simpler explanation

can be furnished by the Neo-Lamarckians, on lines similar to those

upon which I have supposed that Weismann’s explanation would run.

For, on their common supposition that the substance of heredity is

particulate, it matters not in the present connexion whether we

suppose the particles to be ids or gemmules. Indeed, it is more in

accordance with the hypothetical endowments of the latter than of

the former, that they should be capable of penetrating the coats of

an ovum, if they can survive the disintegration of their containing

spermatozoön. Nevertheless, thus far it does not seem to me that any

theory belonging to the family of pangenesis can gain any advantage

over the theory of germ-plasm, by appealing to the fact of a previous

sire sometimes affecting the progeny of a subsequent one. The case,

however, is widely different if we turn from animals to plants, thus.

The advantage which any theory of gemmules seeks to gain over the

theory of germ-plasm by an appeal to the fact in question, consists

in supposing that the influence of the previous sire is exercised

in the first instance on the somatic cells of the female. For this

would prove that the germinal elements of the male are capable of

communicating their hereditary qualities, not only by mixing with the

germinal elements of the female (as in ordinary fertilization) but

also by direct contact with the general tissues of the female. And

this again would prove that the fundamental postulate of the theory

of germ-plasm is erroneous—i.e., the postulate of the continuity

of germ-plasm, or of its perpetual restriction to a “sphere” of its

own. This, as all who are acquainted with the literature of the

subject will at once perceive, would be a serious blow to the whole

Weismannian system. But, as we have seen, the current Lamarckian

interpretation of the fact in question involves the supposition of

a physiological machinery so inconceivably complex that instead of

serving to corroborate the theory of gemmules (or of physiological

units) it would go to render that theory incredible[77].

If, however, we turn to plants, we find a considerable number of

facts which unquestionably demonstrate the only point which this

interpretation has been adduced to suggest. For these facts show that,

in not a few cases, the germinal matter of pollen-grains is capable

of asserting its influence beyond the ovules to the somatic tissues

of the ovary, and even to the flower-stalk of the mother plant.

Here, then, we have simple and conclusive evidence of the material

of heredity exercising a direct influence on somatic tissues. How

this well-known fact is to be met by the theory of germ-plasm is a

question which does not seem to have thus far engaged the attention

of Professor Weismann, or of any of his followers. For particulars

touching this phenomenon, so highly important in its relation to the

theory of germ-plasm, I cannot do better than refer to the eleventh

chapter of Darwin’s work on the “Variation of Animals and Plants under

Domestication.”

Again, in the _Contemporary Review_ for May, Mr. Spencer wrote:—

In the essay to which this is a postscript, conclusions were drawn

from the remarkable case of the horse and quagga there narrated,

along with an analogous case observed among pigs. These conclusions

have since been confirmed. I am much indebted to a distinguished

correspondent who has drawn my attention to verifying facts furnished

by the offspring of whites and negroes in the United States. Referring

to information given him many years ago, he says:—“It was to the

effect that the children of white women by a white father had been

_repeatedly_ observed to show traces of black blood, in cases when the

woman had previous connexion with [i. e., a child by] a negro.” At the

time I received this information, an American was visiting me; and,

on being appealed to, answered that in the United States there was an

established belief to this effect. Not wishing, however, to depend

upon hearsay, I at once wrote to America to make inquiries. Professor

Cope of Philadelphia has written to friends in the South, but has

not yet sent me the results. Professor Marsh, the distinguished

palæontologist, of Yale, New Haven, who is also collecting evidence,

sends a preliminary letter in which he says:—“I do not myself know of

such a case, but have heard many statements that make their existence

probable. One instance, in Connecticut, is vouched for so strongly by

an acquaintance of mine, that I have good reason to believe it to be

authentic.”

That cases of the kind should not be frequently seen in the North,

especially nowadays, is of course to be expected. The first of

the above quotations refers to facts observed in the South during

slavery days; and, even then, the implied conditions were naturally

very infrequent. Dr. W. J. Youmans of New York has, on my behalf,

interviewed several medical professors, who, though they have not

themselves met with instances, say that the alleged result, described

above, “is generally accepted as a fact.” But he gives me what I think

must be regarded as authoritative testimony. It is a quotation from

the standard work of Professor Austin Flint, and runs as follows:—

A peculiar and, it seems to me, an inexplicable fact is, that previous

pregnancies have an influence upon offspring. This is well known

to breeders of animals. If pine-blooded mares or bitches have been

once covered by an inferior male, in subsequent fecundations the

young are likely to partake of the character of the first male, even

if they be afterwards bred with males of unimpeachable pedigree.

What the mechanism of the influence of the first conception is,

it is impossible to say; but the fact is incontestable. The same

influence is observed in the human subject. A woman may have, by a

second husband, children who resemble a former husband, and this is

particularly well marked in certain instances by the colour of the

hair and eyes. A white woman who has had children by a negro may

subsequently bear children to a white man, these children presenting

some of the unmistakable peculiarities of the negro race[78].

Dr. Youmans called on Professor Flint, who remembered “investigating

the subject at the time his larger work was written [the above is

from an abridgment], and said that he had never heard the statement

questioned.”

Some days before I received this letter and its contained quotation,

the remembrance of a remark I heard many years ago concerning dogs, led

to the inquiry whether they furnished analogous evidence. It occurred

to me that a friend who is frequently appointed judge of animals at

agricultural shows, Mr. Fookes, of Fairfield, Pewsey, Wiltshire, might

know something about the matter. A letter to him brought various

confirmatory statements. From one “who had bred dogs for many years” he

learnt that—

It is a well-known and admitted fact that if a bitch has two litters

by two different dogs, the character of the first father is sure to

be perpetuated in any litters she may afterwards have, no matter how

pure-bred a dog may be the begetter.

After citing this testimony, Mr. Fookes goes on to give illustrations

known to himself.

A friend of mine near this had a very valuable Dachshund bitch, which

most unfortunately had a litter by a stray sheep-dog. The next year

her owner sent her on a visit to a pure Dachshund dog, but the produce

took quite as much of the first father as the second, and the next

year he sent her to another Dachshund with the same result. Another

case:—A friend of mine in Devizes had a litter of puppies, unsought

for, by a setter from a favourite pointer bitch, and after this she

never bred any true pointers, no matter of what the paternity was.

These further evidences, to which Mr. Fookes has since added others,

render the general conclusion incontestable. Coming from remote

places, from those who have no theory to support, and who are some

of them astonished by the unexpected phenomena, the agreement

dissipates all doubt. In four kinds of mammals, widely divergent in

their natures—man, horse, dog, and pig—we have this same seemingly

anomalous kind of heredity made visible under analogous conditions.

We must take it as a demonstrated fact that, during gestation, traits

of constitution inherited from the father produce effects upon the

constitution of the mother; and that these communicated effects

are transmitted by her to subsequent offspring. We are supplied

with an absolute disproof of Professor Weismann’s doctrine that the

reproductive cells are independent of, and uninfluenced by, the somatic

cells; and there disappears absolutely the alleged obstacle to the

transmission of acquired characters....

There is one other passage in Dr. Romanes’ criticism—that concerning

the influence of a previous sire on progeny—which calls for comment.

He sets down what he supposes Weismann will say in response to my

argument. “First, he may question the fact.” Well, after the additional

evidence given above, I think he is not likely to do that; unless,

indeed, it be that along with readiness to base conclusions on things

“it is easy to imagine” there goes reluctance to accept testimony which

it is difficult to doubt. Second, he is supposed to reply that “the

germ-plasm of the first sire has in some way or another become partly

commingled with that of the immature ova”; and Dr. Romanes goes on

to describe how there may be millions of spermatozoa and “thousands

of millions” of their contained “ids” around the ovaries, to which

these secondary effects are due. But, on the one hand, he does not

explain why in such case each subsequent ovum, as it becomes matured,

is not fertilized by the sperm-cells present, or their contained

germ-plasm, rendering all subsequent fecundations needless; and, on

the other hand, he does not explain why, if this does not happen,

the potency of this remaining germ-plasm is nevertheless such as to

affect not only the next succeeding offspring, but all subsequent

offspring. The irreconcilability of these two implications would,

I think, sufficiently dispose of the supposition, even had we not

daily multitudinous proof that the surface of a mammalian ovarium is

not a sperm-atheca. The third difficulty Dr. Romanes urges is the

inconceivability of the process by which the germ-plasm of a preceding

male parent affects the constitution of the female and her subsequent

offspring. In response, I have to ask why he piles up a mountain of

difficulties based on the assumption that Mr. Darwin’s explanation of

heredity by “Pangenesis” is the only available explanation preceding

that of Weismann? and why he presents these difficulties to me more

especially, deliberately ignoring my own hypothesis of physiological

units? It cannot be that he is ignorant of this hypothesis, since the

work in which it is variously set forth (“Principles of Biology,” §§

66-97) is one with which he is well acquainted: witness his “Scientific

Evidences of Organic Evolution”; and he has had recent reminders of

it in Weismann’s “Germ-plasm,” where it is repeatedly referred to.

Why, then, does he assume that I abandon my own hypothesis and adopt

that of Darwin, thereby entangling myself in difficulties which my

own hypothesis avoids? If, as I have argued, the germ-plasm consists

of substantially similar units (having only those minute differences

expressive of individual and ancestral differences of structure), none

of the complicated requirements which Dr. Romanes emphasises exists,

and the alleged inconceivability disappears.

To this I responded, in the _Contemporary Review_ for June:—

With regard to the influence of a previous sire, I ventured in my

article to show that, even supposing it to be a fact, the phenomena

concerned would not constitute any valid evidence against Weismann’s

theory of germ-plasm, and, of course, still less would “they prove

that while the reproductive cells multiply and arrange themselves

during the evolution of the embryo, some of their germ-plasm passes

into the mass of somatic cells constituting the parental body, and

becomes a permanent component of it,” with the result that the

phenomena in question “are simply fatal to Weismann’s hypothesis.”

For a much simpler and more probable explanation is to be found in

supposing that the unused germ-plasm of the first sire may survive

the disintegration of its containing spermatozoa in the Fallopian

tubes of the female, and thus gain access to the hitherto unripe ova

_directly_, instead of first having to affect the whole maternal

organism, and then being _reflected_ from it to them. I showed, at

some length, how immensely complex the mechanism of any such process

would necessarily have to be; and for the purposes of exposition I

employed the terminology of Darwin’s theory of Pangenesis. Mr. Spencer

now says: “In response, I have to ask why he [I] piles up a mountain

of difficulties based on the assumption that Mr. Darwin’s explanation

of heredity by ‘Pangenesis’ is the only available explanation

preceding that of Weismann? and why he presents these difficulties

to me more expecially, deliberately ignoring my own hypothesis of

physiological units?” Now my answer to this is very simple. I do not

hold a brief for Weismann. On the contrary, I am in large measure an

opponent of his views; and my only object in publishing my previous

article was to save the theory of use-inheritance from what seemed

to me the weaker parts of Mr. Spencer’s advocacy, while thus all the

more emphasizing my acceptance of its stronger parts. Therefore,

the impression which he seems to have gained from my attempts at

impartiality is entirely erroneous. Far from “deliberately ignoring”

any of his arguments or hypotheses which seemed to me at all available

on the side of use-inheritance, I everywhere endeavoured to make the

most of them. And, as regards this particular instance, I expressly

used the term “gemmules,” instead of “physiological units,” simply

because I could not see that, as far as my “mountain of difficulties”

was concerned, it could make one atom of difference which term I

employed. It now appears, however, that, in Mr. Spencer’s opinion,

there is some very great difference. For, while he allows that

the “mountain of difficulties” which I have “piled up” against

his interpretation of the alleged phenomena would be valid on the

supposition that the ultimate carriers of heredity are “gemmules,” he

denies that such is the case if we suppose these ultimate carriers to

be “physiological units.” For this statement, however, he gives no

justification; and, as I am unable to conceive wherein the difference

lies, I sincerely hope that in any subsequent editions of his

pamphlet Mr. Spencer will furnish the requisite explanation. Gladly

substituting the words “physiological units” wherever I have used the

word “gemmules,” I am genuinely anxious to ascertain how he would

overcome the “mountain of difficulties” in question. For I do not

regard the subject as one of mere dialectics. It is a subject of no

small importance to the general issue, Weismann _versus_ Lamarck; and,

therefore, if Mr. Spencer could show that the phenomena in question

make exclusively in favour of the latter, as he alleges, he might

profitably inform us in what way he supposes them to do so.

In conclusion, I would like to take this opportunity of explaining

that my former article was written in Madeira, where I did not receive

a copy of Weismann’s most recent work, entitled _The Germ-plasm_,

until the _Contemporary Review_ for April was being printed off. Thus,

I was not then aware that in this work Professor Weismann had fully

anticipated several of Mr. Spencer’s criticisms—including this

matter of the influence of a previous sire. Here he adopts exactly the

position which in my article I surmised that he would; so that, to

all who have read _The Germ-plasm_, it must have appeared that I was

prophesying after the event. Hence the need of this explanation.

Lastly, in the same issue of the _Contemporary Review_, Mr. Spencer

explained:—

Mr. Darwin’s hypothesis of Pangenesis implies not only that the

reproductive cell must contain numerous kinds of gemmules derived from

different organs, but that the numbers of these gemmules must bear

to one another something like the proportions which the originating

organs bear to one another in size. The conception involves many

different _kinds_, whose numbers are in many different _proportions_,

and I supposed the difficulty alleged was, that for the influence

of a previous sire to be communicated from the growing f[oe]tus to

the mother would imply not only the transfer of the various kinds of

gemmules derived from him, but also maintenance of their numerical

proportions, and that again these gemmules, diffused throughout the

maternal system, would have to be transferred in these proportions to

the subsequently formed ova. No such difficulties arise if the units

conveying hereditary characters are of one kind only.

From this it is apparent that Mr. Spencer has misunderstood “the

difficulty alleged,” and that the desired explanation is not yet

forthcoming. I did not say anything about “kinds” or “proportions”

of the carriers of heredity; my difficulty is to conceive of any

mechanism whereby these carriers can first directly influence the

somatic-cells of the mother, and then indirectly reflect this influence

upon her germ-cells. Also, I cannot see any obvious necessity for the

intervention of the “embryo” in the process.

GLOSSARY.

=Acquired characters.=—_See_ Somatogenetic characters.

=Amphigony= (=Häckel=).—Sexual reproduction.

=Amphimixis= (=Weismann=).—The mingling of the hereditary substances

of two individuals in an act of sexual union.

=Ancestral germ-plasm.=—_See_ p. 123.

=Asexual Reproduction.=—In which there is no liberation of special

germ cells containing the potentiality of the adult organism, but

in which the same object is effected by the liberation of buds,

overgrowths, &c., which develop into the parent form. There are many

forms of a-sexual reproduction.

=Atavism.=—The abnormal occurrence in existing species of characters

which were peculiar to ancestral species, e.g., see _Darwin and after

Darwin_, 2nd ed., Part I, p. 94.

=Biophore.=—_See_ p. 123.

=Blastogenetic characters.=—_See_ Plasmogenetic characters.

=Calyx.=—The outermost covering of the flower, which protects it

before opening. Its position and precise function vary.

=Cell nucleus.=—A spherical or ovoid body embedded in the cell

protoplasm, which has important functions in cell division and in

reproduction. It consists of chromatin and achromatin. There are often

several nuclei in one cell, whilst some cells have not been shown to

have a nucleus at all.

=Cessation of Selection= (=Romanes=).—_See_ Panmixia.

=Chromatin threads.=—Immediately before a cell divides the nucleus is

resolved into chromatin fibres or threads and an achromatin matrix.

These chromatin fibres are then marshalled into either rods or loops,

&c., as the division of the cell proceeds (see _Darwin and after

Darwin_, figs. 36, 37, and 38). Subsequent changes in the threads

conclude the division (for a description of which consult the account

above).

=Chromosomes.=—_See_ Chromatin threads.

=Compositae.=—Plants in which the inflorescence consists of numerous

small flowers brought together into a dense head, the base of which is

enclosed by a common envelope (e.g. the Daisy, Dandelion, &c.).

=Congenital characters.=—_See_ Plasmogenetic characters.

=Conjugation.=—This term is applied to a process observed in

the Protozoa (q. v.), which seems to correspond to the sexual

reproduction of the Metazoa (q. v.). The majority of the Protozoa

cannot long continue to reproduce themselves a-sexually without

becoming degenerate, or rather without becoming altogether extinct.

Two individuals (as a rule) consequently unite either temporarily or

permanently. In the former case, an exchange of material is effected;

and in the latter, complete fusion takes place.

=Correlation.=—The normal coincidence of one phenomenon, character,

&c., with another.

=Cytoplasm.=—_See_ pp. 30 and 32.

=Determinant.=—_See_ p. 123.

=Ectoblast.=—Syn. of epiblast and ectoderm. The general result of

the division of a fertilized ovum is a two-layered ball of cells (a

gastrula). The outer layer is called the ectoblast and the inner layer

the entoblast. (See _Darwin and after Darwin_, p. 137 _et seq._).

=Embryology.=—Hence embryogenesis, &c. The study of the development

or the early growth of the individual.

=Entoblast.=—Syn. of hypoblast and endoderm. _See_ Ectoblast.

=Epigenesis= (=Harvey=).—The theory that organisms are formed by the

development of the egg itself, and not by the expansion of a miniature

within the egg (preformation).

=Fallopian Tubes.=—The tubes through which the spermatozoa pass to

effect fertilization, and through which the ova pass from the ovary to

the uterus.

=Fission.=—Syn. of fissiparous separation. The breaking into two

(without karyokinesis—q. v.) of a cell, which has, by overgrowth,

disturbed its physiological equilibrium. This process is almost

mechanical.

=Formative material.=—_See_ p. 56.

=Gemmation.=—That form of a-sexual reproduction known as budding.

=Gemmules= (=Darwin=).—Minute granules, formed by the division of

the general body-cells, which are supposed to be dispersed throughout

the entire system. These themselves multiply by division, and are

collected from all parts of the body to constitute the sexual elements.

=Germ-plasm.=—_See_ p. 32.

=Hydroids.=—Belong to a division (Hydrozoa) of the stinging-animals

or Coelenterata. They occur both in the sea and in fresh water, and

are solely polypoid (i.e. tubular and tentacled).

=Hydromedusae.=—Also Hydrozoans. Hydroid colonies with special

sexually reproductive persons, which are often liberated as floating

bells or discs.

=Idio-plasm= (=A and B=).—_See_ pp. 31 and 32.

=Ids.=—_See_ p. 123.

=Invertebrata.=—Animals with a dorsal heart and without a backbone.

=Karyokinesis.=—The changes which are observed in the nucleus both

immediately before and after cell division. _See_ Chromatin threads.

=Lamarckian factors.= _See_ Somatogenetic characters. _Also_

Neo-Lamarckians.

=Metaphyta.=—Multicellular plants (q. v.).

=Metazoa.=—Multicellular animals (q. v.).

=Micellae= (=Nägeli=).—_See_ Molecules, with which they are identical.

=Microaomata.=—The protoplasm of certain vegetable cells is in

places characterized by the presence of minute corpuscles, which

may be regarded as part of the protoplasm, and are certainly of a

protoplasmic nature. These are termed Microsomata.

=Molecules= (=Weismann=).—_See_ p. 122.

=Multicellular organisms.=—Organisms composed of many cells, as

distinguished from the Unicellular organisms, where each individual is

constituted of only one cell.

=Natural Selection.=—Survival of the Fittest in the struggle for

existence. For a full account of the process see _Darwin and after

Darwin_, p. 251 _et seq._

=Neo-Darwinians.=—Those who believe that Natural Selection has been

the only modifying influence in the evolution of species, and that the

material for its action has been only plasmogenetic characters (q. v.).

=Neo-Lamarckians.=—Those who hold that organic evolution has

been effected solely by means of the occurrence and preservation

(inheritance) of somatogenetic characters (q. v.).

=Nuclear Thread or Loops.=—_See_ Chromatin threads.

=Nucleo-plasm.=—_See_ pp. 30 and 32.

=Nucleus.=—_See_ Cell nucleus.

=Nutritive congenital characters.=—_See_ p. 64.

=Ontogenetic grades.=—_See_ p. 35.

=Ontogeny.=—The life history of the individual, as distinguished from

the ancestral history of the race (Phylogeny).

=Ova.=—Eggs—the product of the female reproductive gland (ovary or

ovarium).

=Ovule.=—The seed in its earliest condition.

=Pangenesis= (=Darwin=).—The theory of Heredity by gemmules (q. v.).

=Panmixia= (=Weismann=).—The condition of free intercrossing, i.e.

where Natural Selection (q. v.) cannot act.

=Parthenogenesis.=—A degenerate form of sexual reproduction, in which

the egg develops without having been fertilized by the male element.

=Phylogeny.=—The ancestral history of the race, as distinguished from

the life history of the individual (Ontogeny).

=Physiological Units= (=Spencer=).—Special units which it is inferred

a plant or animal of any species is made up of, and in all of which

dwells the intrinsic aptitude to aggregate into the form of that

species.

=Plasma.=—The constituent material of cells, e. g. germ-plasma (of

sexual-cells), somatoplasma (of body-cells).

=Plasmogenetic characters.=—Variations due to admixtures of

germ-plasm in acts of sexual fertilization (and therefore present at

birth), as distinguished from somatogenetic characters—variations

which have been acquired independently of germ-plasm. _See_

Somatogenetic characters.

=Polar bodies.=—Before an egg is fertilized the nucleus moves towards

the periphery and divides twice. The two cells that are thus formed

are the polar bodies. The extrusion of polar bodies is _probably_

universal among animals, but only one polar body is extruded from

parthenogenetic ova. See _Darwin and after Darwin_, pp. 125 and 126.

=Preformation.=—The old conjecture (1672—Malpighi) that the

development of an embryo was merely the expansion or unfolding of a

miniature of the adult within the egg.

=Protophyta.=—Unicellular plants (q. v.).

=Protoplasm.=—Living matter.

=Protozoa.=—Unicellular animals (q. v.).

=Representative Congenital characters.=—_See_ p. 65.

=Reversion.=—_See_ Atavism.

=Rudimentary Organs.=—Usually considered a synonym of the term

“vestigial characters,” and is the name under which are included

all those organs which, either from having become useless or from

other causes, have been much reduced in size, e.g. the muscles

of the external ear in man (see _Darwin and after Darwin_, p.

76), &c. Latterly the former expression has been used to describe

organs in process of development (e.g. the electric organ of the

skate—_loc.cit._, p. 365 _et seq._), whilst the latter is made to

embrace all those organs in process of elimination.

=Soma.=—A general term descriptive of the whole mass of the

body-cells of an organism.

=Somatic-idio-plasm.=—_See_ p. 32.

=Somatogenetic characters.=—Characters _acquired_ by the soma (i. e.

variations acquired after birth by the action of the environment),

as distinguished from characters _produced_ and potentially present

from the first by a union of two masses of germ-plasm—plasmogenetic

characters (q. v.).

=Somatoplasma-plasm.=—_See_ p. 32.

=Specialized congenital characters.=—_See_ p. 65.

=Spermathecae.=—Organs for the storing of the seminal fluid received

in copulation.

=Spermatogenesis.=—The precise development of spermatozoa.

=Spermatozoa.=—The essential elements in the male seminal fluid, and

secreted by the testis—the male reproductive gland.

=Stirp= (=Gallon=).—_See_ p. 58.

=Telegony.=—_See_ p. 141.

=Unicellular Organisms.=—Organisms composed of a single cell

only, as distinguished from those consisting of aggregations of

cells—Multicellular organisms.

=Vertebrata.=—Animals with a backbone and a ventral heart.

=Vestigial Organs.=—_See_ Rudimentary organs,

=Xenia.=—_See_ p. 141.

INDEX.

Acquired characters, definition of, 5;

inheritance of, 6, 15, 49, 57, 60, 67, 69, 71, 81, 83-84, 93-96,

104, 107, 110-111, 127, 173, _et seq._;

Galton on inheritance of, 62, 106.

Adaptive development, Weismann on, 19.

Algae, De Vries on the chromatophores of, 83, 111.

Amphigony, the cause of individual hereditary variation, 91, 100-101.

Amphimixis, _see_ Sexual propagation.

Ancestral germ-plasm, 123.

Atavism, 3, 91, 105.

=Bary, De=, on Weismann’s theory, 152.

Basidiomycetes, 90.

Begonia, regeneration in, 4, 52.

Biophores, 123.

Body-cells, and germ-cells, 29.

=Brooks=, theory of heredity, 2.

Bud-variation, 90, 94, 96, 98-99;

Weismann on, 95, 97, 161;

Fritz Müller on, 95.

Butterflies, climatic varieties of and Weismann’s theory, 67-68,

127-128.

=Candolle, De=, on inheritance of acquired characters in plants, 93.

“Carriers of Heredity,” 32, 38, 70, 78, 122.

Cessation of Selection, _see_ Panmixia.

Chromatophores, of Algae, 83, 111.

Compositae, pollen of, 5.

Congenital variations, definition of, 5;

inheritance of, 6, 110;

sexual propagation, the cause of, 11;

Darwin on, 13;

origin of, 23, 25, 100, 102;

nutritive congenital changes, 64;

examples of, 64;

specialized congenital changes, 65;

representative congenital changes, 65;

Galton on, 134.

Continuity of germ-plasm, _see_ Germ-plasm.

Crustacea, and the inheritance of acquired characters, 94.

Cuttings, and bud-variation, 98.

_Cytisus adami_, grafting of, 127.

=Darwin, Charles=, and Pangenesis, 2, 26;

arguments in favour of pangenesis, 3, 59;

on the cause of congenital variations, 13;

comparison of his theory of heredity with that of Weismann, 52, 55,

73, 92, 105-106, 115, 133, 173 _et seq._;

on germ and somatic-cells, 76;

on the influence of pollen upon somatic tissues, 79-80;

on graft-hybridization, 83;

on bud-variation, 95;

on the causes of variation, 102, 161;

on the inheritance of acquired characters, 107, 111-112;

on Xenia, 144;

on sexual union, 154.

Death, Weismann on the origin of, 8, 10;

in plants, 10.

Determinants, 123.

Direct action of environment, on unicellular organisms, 15, 23.

=Elsberg=, theory of heredity, 2.

Environment, direct action of on Protozoa, 15.

Evolution, _see_ Organic evolution.

=Flint, Prof. Austin=, on Telegony, 204.

=Focke=, on Xenia, 141, 144.

“Formative material,” and germ-plasm, 56.

Fungi, Prof. Vines on Basidiomycetes, 90.

=Galton, Francis=, theory of heredity (stirp), 2;

and Weismann’s, 51, 58-59, 69, 73, 92, 105-106, 108, 115, 129,

130 _et seq._;

on gemmules, 60;

on inheritance of acquired characters, 62, 69, 107;

and stability of the material basis of heredity, 63;

on origin of sexual reproduction, 103, 167.

=Gärtner=, on Malva, 80;

on inheritance of acquired characters in plants, 93.

Gemmules, 2;

Darwin on the size of, 4;

and germ-plasm, 52, 55, 58, 92, 105;

and stirp, 58;

Galton on, 60.

Generative cells of the Hydromedusae, Weismann on, 71, 109;

example of continuity of germ-plasm, 72-73.

Germ-cells, and body-cells, 29, 75-77;

nucleo-plasm of, 30;

number of, 43, 45.

Germ-plasm, Weismann’s theory of, 5, 105, 173 _et seq._;

immortality of, 9, 24;

continuity of, 9, 18, 49, 56-67, 69-70, 72, 75, 78, 86-87, 104-105,

109-110, 114, 120, 168;

differences in, 12;

origin of, 17;

independence of, 19;

and natural selection, 21;

stability of, 22, 49, 57, 66, 86-89, 91-93, 99-100, 104-105, 109,

112-114, 151 _et seq._;

lodged in nucleus, 29;

and somato-plasm, 29, 81, 110;

the modification of, 36;

examination of Weismann’s theory of, 48;

Weismann’s theory of and Pangenesis, 52;

and gemmules, 52, 55, 58, 105-106, 121;

multiplication of in the general cellular tissues of plants, 53;

De Vries on, 54;

Differentiation of, 55;

and “formative material,” 56;

and stirp, 58-59, 61, 75, 106;

and somatic-idioplasm, 69;

as a basis of heredity, 70;

ancestral germ-plasm, 123.

Grafting, and the effect of the somatic-tissues on the germinal

elements, 81-82;

Darwin on, 83;

and bud-variation, 98;

Weismann on, 126.

=Häckel=, theory of heredity, 2.

=Hartog, Prof. M.=, on Weismann, 155;

on sexual propagation, 166-167.

Healing of wounds, 34.

=Henslow, Rev. G.=, on regeneration in plants, 53.

Heredity, various theories of, 2, 49, 70;

statement of Weismann’s theory of, 17;

modification of Weismann’s theory of, 28, 46, 52, 65, 68, 75,

163 _et seq._;

the nucleus and, 29;

“carriers of,” 32, 38, 70, 78, 122;

theory of and histology, 38;

examination of Weismann’s theory of, 48, 105, 117;

comparison of Weismann’s, Darwin’s, and Galton’s theories of, 51,

105-106;

criticism of Weismann’s theory of by Strasburger, 51;

the material basis of, 61, 63.

=Hertwig, O.=, theory of heredity, 2;

on polar bodies, 46, 125.

=Hildebrand=, or effect of pollen upon somatic tissues (Xenia), 80;

on Orchideae, 80.

=His=, theory of heredity, 2.

=Hoffmann=, on the inheritance of acquired characters, 93-4, 114.

Hydromedusae, Weismann on generative cells of, 71, 109;

illustrate continuity of germ-plasm, 73-73.

Identical twins, 41.

Idio-plasm, Nägeli’s term, 31;

A and B, 31-32;

self-multiplication of, 34;

amount of idio-plasm A in the nucleus, 40.

Ids, 123.

Individual differences, Weismann, 39, 41, 43.

Influence of a previous sire upon the progeny of the same dam,

_see_ Telegony.

Influence of external conditions, _see_ Acquired characters.

Influence of pollen upon somatic tissues, _see_ Xenia.

Inheritance of acquired characters, _see_ Acquired characters.

Invertebrates, Weismann on sexual apparatus of, 72, 74, 109.

Jelly-fish, regeneration in, 4.

=Jordan=, on inheritance of acquired characters in plants, 93.

Karyokinesis, 37.

=Lamarck=, Weismann and, 16, 21.

Lamarckian factors, importance of, 57, 59, 62, 65, 67, 69, 82,

106-108, 111-112, 128, 147.

Life, duration of, 7, 10.

=Malingié-Nouel=, on Telegony, 193 _et seq._

Malva, Gärtner on, 80.

=Maupas=, on the Protozoa, 101, 148.

Metazoa and Metaphyta, cause of mortality of, 7, 24, 148;

relation of progeny to parents in, 16;

transmission of acquired characters in, 16;

propagation in, 51.

=Mivart=, on inheritance of acquired characters, 94.

Molecules, 54, 123.

=Morton, Earl of=, on Telegony, 192.

=Müller, Fritz=, on bud-variation, 95.

Multicellular organisms, _see_ Metazoa and Metaphyta.

=Nägeli=, theory of heredity, 2;

and idio-plasm, 31, 187;

and germ-plasm, 36;

on inheritance of acquired characters in plants, 93.

Natural selection, the cause of death, 8;

action of, 20;

the material for the operation of, 13, 57;

not the cause of sexual propagation, 13-14;

and the Protozoa, 15, 101-102;

and germ-plasm, 21;

sole cause of organic evolution, 25, 59, 111, 114.

=Nouel, Malingié=, on Telegony, 193 _et seq._

Nucleo-plasm, of germ and somatic cells, 30.

Nucleus, alone contains germ-plasm, 29;

contains two substances, 33;

and heredity, 37;

and polar bodies, 40;

amount of idio-plasm A in, 40.

Nutritive congenital changes, 64.

Orchideae, Hildeband on, 80.

Organic evolution, the cause of, 25;

Weismann’s theory of, 26, 48, 50, 58, 66, 68, 87, 100, 104, 106-108,

114-115, 147.

Ova, Weismann on the size of, 39.

=Pallas=, on variability, 154.

Pangenesis, Darwin’s theory of, 2, 26;

and Weismann’s theory of, 52, 55, 71, 73, 121;

and Panmixia, 59-60;

Galton on, 60.

Panmixia, and Pangenesis, 59-60.

Parthenogenetic organisms, and natural selection, 15;

no congenital variations in, 72, 75.

Parthenogenetic ova, Weismann on, 45, 89, 91, 109.

Phylogenesis, 34.

Physiological isolation, of germ-cells, 74.

Plants, reproductive cells of, 74;

influence of pollen upon somatic tissues of (Xenia), 78-80;

bud-variation in, 90, 94-99;

Hoffmann’s investigations on the inheritance of acquired characters

in, 93.

Polar bodies, Weismann on, 40, 46, 125;

examination of Weismann’s explanation of, 42;

O. Hertwig on, 46, 125.

Protophyta, natural selection and, 114.

Protozoa, immortality of, 7;

and natural selection, 15, 114;

origin of species of, 15, 102;

action of environment on, 15;

Maupas on, 101.

Regeneration, in sea-anemones and jelly-fish, 4, 35;

of an entire organism, 34;

Weismann on, 51 _et seq._;

in Begonia, 52;

Rev. G. Henslow on, 53;

and stirp, 59.

Rejuvenescence, 166.

Representative congenital changes, 65.

Reproduction, essential meaning of sexual, 8, 11;

in the Protozoa, 16;

somatic, 35.

Reproductive elements, potential immortality of, 9;

of Vertebrates and Plants, 74.

Reversion, 3, 91, 105.

=Roux=, on the principle of “struggle,” 139.

Sea-anemones, regeneration in, 4.

Sexual apparatus of Invertebrates, Weismann on, 72, 74.

Sexual-cells and somatic-cells, 75-77, 81, 84.

Sexual propagation, essential meaning of, 8, 11, 87;

sole cause of congenital variations, 12, 89-90, 102, 135, 141, 153,

158;

did not arise through the agency of natural selection, 13-14;

in multicellular organisms, 51;

Galton on the origin of, 103;

in _Cytisus adami_, 127.

Significance of sexual reproduction, _see_ Sexual Reproduction.

Somatic-cells, nucleo-plasm of, 30;

and sexual cells, 75-77, 81, 84.

Somatic-idio-plasm, 32-33;

and germ-plasm, 69.

Somatic reproduction, 35, 52.

Somato-plasm and germ-plasm, 29.

Specialized congenital changes, 65.

Species, Weismann on the origin of new, 100-101.

=Spencer, Herbert=, theory of heredity, 2;

on Telegony, 191 _et seq._

Stability of germ-plasm, _see_ Germ-plasm.

Stirp, and gemmules, 58-59, 61;

and somatic tissues, 60;

and the germinal cells of Hydromedusae, 73;

and germ-plasm, 75, 92, 106, 133.

=Strasburger=, on Weismann’s theory of heredity, 51;

on the origin of sexual propagation, 167.

_Stylonichia_, Maupas on, 101.

Summary, 103.

Telegony, 77-79, 110, 141 _et seq._, 191 _et seq._

Transmission of acquired characters, _see_ Acquired characters.

Twins, identical, 41.

Unicellular organisms, reproduction of, 16;

action of environment on, 23, 147 _et seq._;

potentially immortal, 23;

natural selection and the, 24, 57, 114;

and the origin of hereditary individual variations, 100.

Variation, _see_ Congenital variations, Acquired characters, &c.;

Darwin on the causes of, 102;

Weismann on the origin of, 153.

Vertebrates, reproductive cells of, 74.

Vestigial organs, persistence of, 91.

=Vines, Prof. S.=, criticism on Weismann, 14, 75, 90, 99, 152, 178;

on the Basidiomycetes, 90.

=Vries, De=, theory of heredity, 2;

on germ-plasm, 54;

on the chromatophores of Algae, 83, 111;

on Xenia, 144.

=Weismann, Prof. August.=, theory of germ-plasm, 5, 17, 173 _et seq._;

on the duration of life, 7, 10;

on the essential meaning of sexual propagation, 11, 103, 135, 141;

on natural selection as the origin of sexual reproduction, 14;

on Prof. Vines’ criticism, 14, 90, 99, 178 _et seq._;

on the Protozoa and natural selection, 15, 102;

on Lamarck, 16;

on adaptive development, 19;

and natural selection, 21;

summary of theory of germ-plasm, 23;

theory of organic evolution, 26, 48, 50, 58, 66, 68, 87, 100, 104,

106-108, 114-115, 147;

modifications of theory of heredity, 28, 46, 52, 65, 68, 75,

163 _et seq._;

and of self-multiplication of idio-plasm, 34;

on “ontogenetic grades,” 35, 53;

on the modification of germ-plasm, 36;

on chromatin, 38;

on individual differences, 39, 41, 43;

on the size of ova, 39;

on polar bodies, 40, 42, 46, 125;

on the number of germ-cells, 44-45;

on parthenogenetic ova, 45, 89, 91;

examination of his theory of germ-plasm or heredity, 48, 85;

on the stability and continuity of germ-plasm, 49, 63, 66, 86-89,

91-93, 99-100, 103-105, 107, 109-110, 112-114, 120, 151, 158;

comparison of his theory with those of Darwin and Galton, 51, 58;

on Strasburger’s criticism of his theory, 52;

on the multiplication of germ-plasm in the general cellular tissues

of plants, 53;

on regeneration in plants, 53;

anticipated by Galton, 59, 68;

and Galton, 63, 130 _et seq._;

on transmission of acquired characters, 67, 83, 96, 111, 127;

and his critics, 70;

on the Hydromedusae, 71, 109;

on the sexual apparatus of Invertebrates, 72;

and the influence of germ-cells upon somatic tissues (Telegony and

Xenia), 80-81, 196 _et seq._;

and the significance of grafting, 81-82, 126;

and vestigial characters, 92;

on Hoffmann’s investigations, 93;

on bud-variation, 95, 97, 161;

on the origin of hereditary individual variations, 100-101;

on the origin of new species, 101.

Wounds, healing of, 34.

Xenia, 78-81, 110, 141, 144, _et seq._

THE END.

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FOOTNOTES:

[1] Considerable portions of this chapter have already appeared as an

article in the _Contemporary Review_ for May, 1890. My thanks are due

to the editor for kindly allowing me to reproduce them here.

[2] In as far as these sundry theories of heredity are not more or less

intermediate between those of Darwin and Weismann, the differences

have reference either to points of comparative detail, or else to the

introduction of ideas derived from chemistry and physics—whereby it

is sought to show that the principles of chemical combination and of

rhythmic vibration may have a more or less considerable share in the

matter. For my own part I do not see that the introduction of such

ideas has been of any avail in helping—even hypothetically—to explain

the phenomena of heredity; and therefore I do not deem it worth our

while to consider them.

[3] See Appendix.

[4] E.g., _Variation_, &c., vol. i. pp. 197, 398; vol. ii. pp. 237, 252.

[5] Since this chapter was written and sent as a contribution to the

_Contemporary Review_, Professor Weismann has published in _Nature_

(Feb. 6. 1890) an elaborate answer to a criticism of his theory by

Professor Vines (Oct. 24, 1889). In the course of this answer Professor

Weismann says that he does attribute the origin of sexual reproduction

to natural selection. This directly contradicts what he says in his

_Essays_; and, for the reasons given in the text, appears to me an

illogical departure from his previously logical attitude. I herewith

append quotations, in order to reveal the contradiction.

“But when I maintain that the meaning of sexual reproduction is to

render possible the transformation of the higher organisms by means of

natural selection, such a statement is not equivalent to the assertion

that sexual reproduction originally came into existence in order

to achieve this end. The effects which are now produced by sexual

reproduction did not constitute the causes which led to its first

appearance. Sexual reproduction came into existence before it could

lead to hereditary individual variability [i.e., to the possibility

of natural selection]. Its first appearance must, therefore, have had

some other cause [than natural selection]; but the nature of this cause

can hardly be determined with any degree of certainty or precision

from the facts with which we are at present acquainted.”—_Essay on

the Significance of Sexual Reproduction in the Theory of Natural

Selection._ English Translation, pp. 281-282.

“I am still of opinion that the origin of sexual reproduction depends

on the advantage which it affords to the operation of natural

selection.... Sexual reproduction has arisen by and for natural

selection as the sole means by which individual variations can be

united and combined in every possible proportion.”—_Nature_, vol. xli.

p. 322.

How such contradictory statements can be reconciled I do not perceive;

but they furnish a good example of the extreme laxity with which the

term “natural selection” is used by ultra-Darwinians.

[6] The meaning of this term, however, as originally used by Nägeli, he

so greatly changes to suit the requirements of his own theory, that I

think it would have been better had he coined some new one.

[7] I think it is to be regretted that for this other kind of

idio-plasm (i.e., idio-plasm-B) Weismann has not coined some

distinctive name, or some distinctive prefix, such as that which

he sometimes employs when speaking of the other kind (i.e.,

idio-plasm-A)—viz., “somatic-idioplasm.” Also, the interchangeable

manner in which he uses his term “idio-plasm” with the term “

nucleo-plasm,” is somewhat confusing (e.g., pp. 217, 219, 220, 250,

251, &c.). I may add that the word “plasm” in all its combinations

appears to me an unfortunate one, since it seems to betoken a substance

that can be _seen_, instead of merely inferred. But, be this as it

may, the following table of terms employed may be useful for ready

reference:—

Nucleo-plasm = the whole contents of the nucleus of any cell.

Cytoplasm = all the other contents of any cell.

Idio-plasm-A = that portion of nucleo-plasm which “controls” a single

cell.

Idio-plasm-B = that portion of nucleo-plasm which is destined to

construct future cells.

Germ-plasm = undifferentiated idio-plasm-B.

Somato-plasm = idio-plasm-A + cytoplasm.

[8] See close of Appendix.

[9] See Part I, figs. 36, 37, and 38. The substance of this thread, in

the various phases of its segmentation, is the “chromatin,” as there

depicted, and so called because it takes a stain better than other

parts of the nucleus—thus showing some distinctive character.

[10] For an account of the formation and expulsion of these bodies,

see Part I, pp. 125-6. There is now no longer any doubt touching the

statement there made as to the male-cell likewise parting with some of

its nuclear substance prior to fertilizing the female.

[11] In the case of identical twins, both are probably always produced

from the _same_ ovum.

[12] We have no means of estimating exactly the proportional number of

cases in which this is possible, either among the lower or the higher

plants; but it is certainly much greater than Weismann supposes. “How

is it that all plants cannot be reproduced in this way?” he asks, and

then adds,—“No one has ever grown a tree from the leaf of a lime or an

oak, or a flowering plant from a leaf of the tulip or the convolvulus.”

But I am told by botanists that the only reason why the phenomenon thus

appears to be a rare one, is because it is not worth anybody’s while

to grow plants in this way at a necessarily unsuitable season of the

year. Thus, the Rev. George Henslow writes me:—“The fact is that _any_

plant will reproduce itself by its leaves, provided that the cells be

‘embryonic,’ (i.e., the leaf not too near its complete development),

and that it be not too _thin_, so as to provide enough nutriment for

the bud to form till it has roots.”

[13] _Intracellulare Pangenesis_, s. 55.

[14] I employ the term “particles,” instead of “molecules,” because

although Weismann and his followers seem to prefer the latter term, I

can scarcely imagine that they intend to use it in its original, or

chemical, sense.

[15] This principle will be considered at some length in my next volume.

[16] Galton first published his theory in 1872 (_Proc. R. S._, No.

136), but presented it in a more complete form three years later

(_Contemporary Review_, Dec. 1875, and _Journl. Anthropol. Inst._,

1875).

[17] _Journ. Anthropol. Inst._ 1875, p. 346.

[18] _Essays_, &c., 2nd ed., p. 105.

[19] _Essays_, &c., 2nd ed., p. 100.

[20] See for example, _Essays_, p. 229.

[21] On previous occasions, when inconsistencies have been brought to

the notice of Professor Weismann by his critics, he has complained

that sufficient allowance was not made for the fact of his having

published his sundry essays at different times. This, of course, is

a satisfactory answer in cases where criticism refers to a growing

theory, the later additions to which supersede certain parts of the

earlier construction. But clearly the answer is not available in cases

where one set of statements, touching fundamental principles of the

theory, are directly opposed to others. A logical contradiction is

not affected by dates of publication, and where the contradictory

statements have reference to the vital essence of a theory, it is

equally impossible for the theory to comprise them whether they be

presented simultaneously or successively.

[22] The possibility of any spermatozoa of the first impregnation

surviving to take part in the second is excluded by the fact that the

phenomenon occurs in mammals, and, apparently, may extend over two or

three litters.

[23] Possibly the school of Weismann may simply refuse to accept the

facts, which are confessedly rare, and, in many of the cases alleged,

dubious. In other cases, however, the evidence is sufficient to have

satisfied the cautious judgement of Darwin, who has discussed it in

detail. Therefore, even if the Neo-Darwinians repudiate this evidence,

at least they ought to state that such is the position which they adopt.

[24] _Nature_, Feb. 6th, 1890.

[25] _Nature_, vol. xl. p. 626.

[26] _Ibid._, vol. xli. p. 322.

[27] In his _Essays_ (vol. i. p. 282) Weismann says:—“If it could be

shown that a purely parthenogenetic species had become transformed

into a new one, such an observation would prove the existence of

some new force of transformation other than selective processes, for

the new species could not have been produced by these latter.” But

now it has been shown that a purely parthenogenetic species can be

transformed into a new one, and therefore it seems desirable to note

that the observation does not so much as tend to prove the existence

of some new force of transformation other than selective processes.

For this most singular statement can only stand on a prior acceptance

of Weismann’s own assumption, as to amphigony being the only possible

cause of individual hereditary variation. Only if we have already, and

with absolute certainty, embraced the whole Weismannian creed, could

we consent to affirm that “natural selection is an impossibility in a

species propagated by a-sexual reproduction.”

[28] What he says is:—“It was only after a greater or less number

of generations had elapsed that a variable proportion of double

flowers appeared, sometimes accompanied by changes in the leaves

and in the colours of the flowers. _This fact admits of only one

interpretation_:—the changed conditions at first produced slight

and ineffectual changes in the idio-plasm of the individual, which

was transmitted to the following generation.... Now, the idio-plasm

of the first ontogenetic grade (viz., germ-plasm) alone passes from

one generation to another, _and hence it is clear that the germ-plasm

itself must have been gradually changed by the conditions of life,

until the alteration became sufficient to produce changes in the

soma, which appeared as visible characters in either flower or

leaf_.”—_Essays_, pp. 426-7; italics mine.

[29] _Nature_, Nov. 14, 1889, p. 41.

[30] _Essays_, 2nd Ed., pp. 331-2.

[31] _Essays_, p. 296.

[32] In this connexion it ought to be observed that Darwin believed the

causes of variation to be internal as well as external—or arising from

“the nature of the organism” no less—or even more—than from “changed

conditions of life.” But although he appears to have entertained the

admixture of hereditary endowments in sexual unions as one of the

causes of variation belonging to the former category, he expressly says

that he did not regard it as the only, or even the main, cause. (See

_Variation_, &c., vol. i, pp. 197, 398; vol. ii, pp. 237, 252.)

[33] See above, p. 54, note.

[34] See _Darwin and after Darwin_, Part I, p. 129.

[35] It must always be remembered that the view adopted by Weismann

touching the nucleus (and more especially the chromosomes) of a

germ-cell being the sole seat of heredity, is still far from having

been established.

[36] _Essays_, vol. ii. p. 122.

[37] _The Germ-plasm_, p. 342.

[38] _The Germ-plasm_, p. 342.

[39] See, however, p. 83, note.

[40] _Essays_, vol. i. p. 101. Italics mine.

[41] _The Germ-plasm_, p. 406.

[42] Galton, _loc. cit._, pp. 343-344.

[43] Professor Weismann still maintains that there is a further

important distinction between the theories of pangenesis and

germ-plasm, in that the one is pre-formative while the other is

epigenetic. But I am still unable to perceive that such is the case. He

argues, indeed, that his new doctrine of determinants emphasizes this

distinction: the argument, however, appears to me radically unsound.

For instance, he says, “The hereditary continuation in each part is

pre-determined in each part from the germ onwards. The right and left

ears could not possibly resemble each other, if the relative strength

of the hereditary tendencies on both sides were not pre-determined

for all parts of the child by the nature of the paternal and maternal

idants.” Very well. But, if so, the theory of determinants is just as

much pre-formative as is that of gemmules. Or, conversely, the latter

is quite as epigenetic as the former. Both are alike _determinative_,

while neither supposes that the determination is due to a pre-formed

miniature of the future child in the fertilized egg of its mother; but

to a particulate _representation_ in the latter of every heritable part

of the former.

[44] By “germ” Galton means a carrier of heredity, which is capable of

self-multiplication. In these fundamental respects, therefore, it is

equivalent to a “gemmule” on the one hand and a “determinant” on the

other. The three terms are so far synonymous.

[45] _Loc. cit._, p. 338.

[46] _Loc. cit._, p. 339.

[47] _The Germ-plasm_, pp. 199, 220.

[48] pp. 72-4.

[49] _The Germ-plasm_, pp. 383-386.

[50] Quoted from above, p. 78.

[51] _Morph. Journal_, vol. ii.

[52] See Appendix II.

[53] _Essays on Heredity_, vol. ii. pp. 193-4.

[54] See above, pp. 63-67.

[55] _Nature_, vol. xli. p. 322.

[56] _The Germ-plasm_, pp. 414-415. Italics Weismann’s.

[57] _Essays_, vol. i. p. 284.

[58] _The Germ-plasm_, p. 431.

[59] _Variation_ &c., vol. i. p. 398.

[60] _Ibid._, vol. ii. p. 242.

[61] _Nature_, May 11, pp. 28-29.—In 1891-2 Professor Hartog furnished

a criticism of Weismann’s theory of Heredity (_Nature_, vol. 44. p.

613, and _Contemporary Review_, July, 1892). Although disputed at the

time by some of Weismann’s followers in England, this criticism was

one of unquestionable cogency, and has now been recognized as such

by Weismann himself (_The Germ-plasm_, pp. 434-5). The main point

of the criticism had been missed by previous critics of Weismann,

and consisted in revealing an important “difficulty” inherent in the

structure of the theory itself. How far this criticism had the effect

of causing Professor Weismann to abandon his theory of variation being

exclusively due to amphimixis, as Professor Hartog appears to think

(_Nature_, May 11, 1893, p. 28), is immaterial. But it must be observed

that as far back as February, 1890, Professor Weismann in his answer to

Professor Vines’ criticism wrote the passage already quoted on page 152.

[62] It is almost needless to say that no fault is to be found with

Weismann for having thus reversed his opinion touching one of his

fundamental postulates. Consistency is no merit in a man of science;

and least of all where matters of such high speculation are concerned.

I think, however, that it is open to question whether an author of any

kind should suffer an elaborate system of theories to be published and

translated, at the very time when he is himself engaged in producing

another work showing the untenable character of their basal premises.

At any rate, it would have saved his English readers no small trouble

and confusion, if Weismann had added notes to the translations of his

essays on _Polar Bodies_, on _The Significance of Sexual Reproduction_,

and on _Amphimixis_, to the effect that he had abandoned some of their

most distinctive features before the translations had gone to press.

[63] See especially pp. 86-89. All that is there said about the

unicellular organisms is not, in the present connexion, affected

by Weismann’s change of view with regard to them. We have only to

substitute “primordial” or “protoplasmic” for “unicellular,” and nearly

all the points of the criticism remain.

[64] Professor Weismann has now considered more fully than heretofore

the phenomena of bud-variation (_The Germ-plasm_, pp. 439-442); but as

he continues (though with diffidence) to take substantially the same

view of them as that which I have already quoted on pp. 95-96, it is

needless for me to re-discuss the matter here.

[65] “Rejuvenescence” means the renewal of vital energies which is

supposed to result from a fusion of the contents of two cells. For an

excellent discussion of this and the other theories on the object of

sexual propagation, see a brief article by Professor Marcus Hartog,

in the _Contemporary Review_ for July, 1892. Since then Weismann has

published _The Germ-plasm_, and here his main argument against this

theory is that tens, or even hundreds of generations of unicellular

organisms have been observed to succeed one another before any act of

conjugation takes place. But I cannot see that it signifies how many

generations may in different species be proved capable of resulting

from a single act of conjugation. Weismann himself now accepts the

analogy between cell-proliferation as resulting from conjugation in

unicellular organisms, and from fertilization in multicellular. But

even three hundred generations of the former can scarcely be regarded

as equal to all the “ontogenetic stages” of the latter.

[66] This view of the function of sexual propagation is now universally

ascribed to Strasburger, and it is quite true that he has independently

adduced it. But as this was not done until about ten years after it had

been published by Galton, I have designedly associated the idea with

Galton’s name. The following are the words in which it was announced by

him:—

“The necessity of a system of double parentage in complex organisations

is the immediate consequence of a theory of organic units and germs,

as we shall see if we fix our attention upon any one definite series

of unisexual descents, and follow out its history. Suppose we select,

cut off, and plant the second bud, then after it has grown to maturity

we similarly take the second of _its_ buds, and so on consecutively.

At each successive stage there is always a chance of some one or more

of the various species of germs in the stirp dying out, or being

omitted; and of course when they are gone they are lost for ever, and

are irreplaceable by others. From time to time this chance must fall

unfavourably, and will cause a deficiency in some of the structural

elements, and a consequent deterioration of the race. If the loss be

vital, this particular line of descent will of course be extinguished

at once; but on the more favourable supposition, the race will linger

on, submitting to successive decrements in its constituent elements,

until the accumulation of small losses becomes fatal.”—_loc. cit._, p.

333.

Galton also points out a further advantage that is secured by

“amphimixis,” and one which shows the non-necessity of what remains of

Weismann’s theory of polar bodies, thus:—

“There is yet another advantage in double parentage, namely, that as

the stirp whence the child sprang can only be half the size of the

combined stirps of his two parents, it follows that one half of his

possible heritage must have been suppressed. This implies a sharp

struggle for place among the competing germs, and the success, as we

may infer, of the fitter half of their numerous varieties.”—_loc.

cit._, p. 334.

[67] In fact, it seems to me that this is the sole supposition whereby

it can be held that sexual propagation has been developed both “_by_”

and “_for_” natural selection, in order to supply variations as

material for the action of this principle. Natural selection cannot

thus supply the conditions to its own activity, if, as Weismann

supposes, there is but one purpose for it to subserve (see above, pp.

13-15). But, if it is acting for more than one purpose, the “by” and

the “for” argument may hold.

[68] I find that a passage explaining the sense in which I use these

terms has been accidentally omitted from Chapter III, where they are

first introduced; and, as the sheets of that chapter have been already

printed off, I here supply the omission. The terms in italics are not

Weismann’s, and I have employed them merely for the purpose of giving

precision to his views. By “_absolute_ stability of germ-plasm” I mean

to indicate that degree of stability which he has hitherto postulated

as the necessary basis for his doctrine of heritable variations

being solely due to admixtures of germ-plasm in sexual unions. By

“_perpetual_ continuity of germ-plasm” I intend to denote that amount

of continuity which he still postulates as the necessary basis for

his correlative doctrine touching the non-inheritance of acquired

characters.

[69] _Essays_, pp. 76-77, from which the following quotations are

likewise taken _seriatim_.

[70] “Or, more precisely, they must give up as many molecules as would

correspond to the number of the kind of cell in question found in the

mature organism.” Of course by “molecules” Weismann means what Darwin

does by “gemmules.”

[71] If there are such things as gemmules, it appears to me to follow

that the only physiological distinction between the reproductive glands

and glands in general is, that the former discharge their products in

the form of living cells. Even here, however, there appears to be one

analogous case in those salivary glands which discharge the so-called

salivary corpuscles—i.e., nucleated cells, undergoing amoeboid changes

of form, and exhibiting the movements of living protoplasm in their

interior.

[72] _Variation_, &c., 2nd ed., vol. ii. pp. 374-6.

[73] _Nature_, vol. xl. p. 624. Weismann’s answer to this and other

parts of Professor Vines’ criticism where the term “somato-plasm”

occurs, will be considered later on.

[74] Weismann speaks disparagingly of Darwin’s theory as a “theory

of _preformation_” (p. 316). “We must assume,” he adds by way of

explanation, “that each single part of the body at each developmental

stage is, from the first, represented in the germ-cell as distinct

particles of matter, which will reproduce each part of the body at its

appropriate stage as their turn for development arrives.” But must we

not likewise “assume” exactly the same thing in the case of Weismann’s

own theory? To me, at any rate, it appears that the description is

quite as appropriate to germ-plasm as it is to gemmules. Nor can I see

any distinction, even where he seeks to draw it more expressly, as

for instance—“Every detail in the whole organism must be represented

in the germ-plasm by its own special and peculiar arrangement of

the groups of molecules, ... not indeed as the pre-formed germs of

structure (the gemmules of pangenesis), but as variations in its

molecular constitution.” [_Essays_, p. 194.] Again, on page 325 he

gives a foot-note explaining the distinction by alluding to the

controversy between the preformationists and epigenesists. But the

theory of pangenesis does not suppose the future organism to exist in

the egg-cell _as a miniature_: it supposes merely that every part of

the future organism is represented in the egg-cell by corresponding

material particles. And this, as far as I can understand, is exactly

what the theory of germ-plasm supposes; only it calls the particles

“molecules,” and seemingly attaches more importance to the matter of

variations in their arrangement or “constitution,” whatever these vague

expressions may be intended to signify.

[75] ‘Philosophical Transactions of the Royal Society for the Year

1821,’ Part I. pp, 20-24.

[76] Readers who may happen to be acquainted with De Vries’ important

essay on heredity will perceive how well this suggestion fits in with

his modification of Pangenesis.

[77] As already indicated, I cannot gather from his remarks on the

subject which, if any, of the alternative interpretations of the

phenomena that we are considering Mr. Spencer adopts. From the

following sentences it would appear that he assigns yet a third

interpretation, _and this as the only possible one_. For he says of

these phenomena: “They prove that while the reproductive cells multiply

and arrange themselves during the evolution of the embryo, some of

their germ-plasm passes into the mass of somatic cells constituting the

parental body, and becomes a permanent component of it. Further, they

necessitate the inference that this introduced germ-plasm, everywhere

diffused, is some of it included in the reproductive cells subsequently

formed” (_Contemporary Review_, March, p. 452). This appears to

mean that the influence of a previous sire can only be explained by

supposing that the developing embryo inoculates the somatic tissues of

its mother with hereditary material derived from its father, and that

the maternal tissue afterwards reflect some of this material (or its

influence) to the still unripe ovarian ova. If this be the hypothesis

intended, it seems to me more complex than any of the three which I

have suggested. But, be this as it may, we certainly cannot agree

that such an hypothesis is “proved” by the facts, or that the latter

“necessitate” the inference as to its being some of the _embryo’s_

germinal matter which enters the unripe ova.

[78] “A Text Book of Human Physiology.” By Austin Flint, M.D., LL. D.

Fourth edition. New York: D. Appleton & Co. 1888. Page 797.

I tried to breed from the male quagga and a young chestnut mare of