Chapter LII: Part III: of the original edition of the Principles of Psychology

(1855): forming a preliminary which, though indispensable to the
argument there developed, was somewhat parenthetical. Having now to
deal with the general science of Biology before the more special one
of Psychology, it becomes possible to transfer these chapters to
their proper place.

[15] See _Westminster Review_ for April, 1852.--Art. IV. "A Theory of
Population." See Appendix A.

[16] This paragraph replaces a sentence that, in _The Principles of
Psychology_, referred to a preceding chapter on "Method;" in which
the mode of procedure here indicated was set forth as a mode to be
systematically pursued in the choice of hypotheses. This chapter on
Method is now included, along with other matter, in a volume entitled
_Various Fragments_.

[17] Speaking of "the general idea of _life_" M. Comte says:--"Cette idée
suppose, en effet, non-seulement celle d'un être organisé de manière
à comporter l'état vital, mais aussi celle, non moins indispensable,
d'un certain ensemble d'influences extérieures propres à son
accomplissement. Une telle harmonie entre l'être vivant et le
_milieu_ correspondant, caractérise evidemment la condition
fondamentale de la vie." Commenting on de Blainville's definition of
life, which he adopts, he says:--"Cette lumineuse définition ne me
paraît laisser rien d'important à désirer, si ce n'est une indication
plus directe et plus explicite de ces deux conditions fondamentales
co-relatives, nécessairement inséparables de l'état vivant, un
_organisme_ déterminé et un _milieu_ convenable." It is strange that
M. Comte should have thus recognized the necessity of a harmony
between an organism and its environment, as a _condition_ essential
to life, and should not have seen that the continuous maintenance of
such inner actions as will counterbalance outer actions,
_constitutes_ life.

[When the original edition was published Dr. J. H. Bridges wrote to
me saying that in the _Politique Positive_, Comte had developed his
conception further. On p. 413, denying "le prétendu antagonisme des
corps vivants envers leurs milieux inorganiques," he says "au lieu de
ce conflit, on a reconnu bientôt que cette relation nécessaire
constitue une condition fondamentale de la vie réelle, dont la notion
systématique consiste dans une intime conciliation permanente entre
la spontanéité intérieure et la fatalité extérieure." Still, this
"conciliation _permanente_" seems to be a "_condition_" to life; not
that varying adjustment of changes which life consists in
maintaining. In presence of an ambiguity, the interpretation which
agrees with his previous statement must be chosen.]

[18] In further elucidation of this general doctrine, see _First
Principles_, § 25.

[19] In ordinary speech Development is often used as synonymous with
Growth. It hence seems needful to say that Development as here and
hereafter used, means _increase of structure_ and not _increase of
bulk_. It may be added that the word Evolution, comprehending growth
as well as Development, is to be reserved for occasions when both are
implied.

[20] This paragraph originally formed part of a review-article on
"Transcendental Physiology," published in 1857.

[21] When, in 1863, the preceding chapter was written, it had not occurred
to me that there needed an accompanying chapter treating of
Structure. The gap left by that oversight I now fill up. In doing
this there have been included certain statements which are tacitly
presupposed in the last chapter, and there may also be some which
overlap statements in the next chapter. I have not thought it needful
so to alter adjacent chapters as to remove these slight defects: the
duplicated ideas will bear re-emphasizing.

[22] In connexion with this matter I add here a statement made by Prof.
Foster which it is difficult to understand: "Indeed it has been
observed that a dormouse actually gained in weight during a
hybernating period; it discharged during this period neither urine
nor fæces, and the gain in weight was the excess of oxygen taken in
over the carbonic acid given out." (_Text-book of Physiology_, 6th
ed., Part II, page 859.)

[23] In the account of James Mitchell, a boy born blind and deaf, given by
James Wardrop, F.R.S. (Edin. 1813), it is said that he acquired a
"preternatural acuteness of touch and smell." The deaf Dr. Kitto
described himself as having an extremely strong visual memory: he
retained "a clear impression or image of everything at which he ever
looked."

[24] Here, as in sundry places throughout this chapter, the necessities of
the argument have obliged me to forestall myself, by assuming the
conclusion reached in a subsequent chapter, that modifications of
structure produced by modifications of function are transmitted to
offspring.

[25] Whether the _Volvox_ is to be classed as animal or vegetal is a
matter of dispute; but its similarity to the blastula stage of many
animals warrants the claim of the zoologists.

[26] While the proof was in my hands there was published in _Science
Progress_ an essay by Dr. T. G. Brodie on "The Phosphorus-containing
Substances of the Cell." In this essay it is pointed out that
"nucleic acid is particularly characterized by its instability.... In
the process of purification it is extremely liable to decompose, with
the result that it loses a considerable part of its phosphorus. In
the second place it is most easily split up in another manner in
which it loses a considerable part of its nitrogen.... To avoid the
latter source of error he [Miescher] found that it was necessary to
keep the temperature of all solutions down to 0°C., the whole time of
the preparation." These facts tend strongly to verify the hypothesis
that the nucleus is a source of perpetual molecular disturbance--not
a regulating centre but a stimulating centre.

[27] The writing of the above section reminded me of certain allied views
which I ventured to suggest nearly 50 years ago. They are contained
in the _Westminster Review_ for April, 1852, in an article entitled
"A Theory of Population deduced from the General Law of Animal
Fertility." It is there suggested that the "spermatozoon is
essentially a neural element, and the ovum essentially a hæmal
element," or, as otherwise stated, that the "sperm-cell is
co-ordinating matter and the germ-cell matter to be co-ordinated"
(pp. 490-493). And along with this proposition there is given some
chemical evidence tending to support it. Now if, in place of "neural"
and "hæmal," we say--the element that is most highly phosphorized and
the element that is phosphorized in a much smaller degree; or if, in
place of co-ordinating matter and matter to be co-ordinated, we
say--the matter which initiates action and the matter which is made
to act; there is disclosed a kinship between this early view and the
view just set forth. In the last part of this work, "Laws of
Multiplication," which is developed from the essay referred to, I
left out the portion containing the quoted sentences, and the
evidence supporting the conclusion drawn. Partly I omitted them
because the speculation did not form an essential link in the general
argument, and partly because I did not see how the suggested
interpretation could hold of plants as well as of animals. If,
however, the alleged greater staining capacity of the male generative
nucleus in plants implies, as in other cases, that the male cell has
a larger proportion of the phosphorized matter than the other
elements concerned, then the difficulty disappears.

As, along with the idea just named, the dropped portion of the
original essay contains other ideas which seem to me worth
preserving, I have thought it as well to reproduce it, in company
with the chief part of the general argument as at first sketched out.
It will be found in Appendix A to this volume.

[28] Unfortunately the word _heterogenesis_ has been already used as a
synonym for "spontaneous generation." Save by those few who believe
in "spontaneous generation," however, little objection will be felt
to using the word in a sense that seems much more appropriate. The
meaning above given to it covers both Metagenesis and
Parthenogenesis.

[29] Prof. Huxley avoids this difficulty by making every kind of Genesis a
mode of development. His classification, which suggested the one
given above, is as follows:--

{ Growth
{ Continuous {
{ { Metamorphosis
{
Development {
{ { Metagenesis
{ { Agamogenesis {
{ Discontinuous { { Parthenogenesis
{ Gamogenesis

[30] The implication is that an essentially similar process occurs in
those fragments of leaves used for artificial propagation. Besides
the Begonias in general, I learn that various other plants are thus
multiplied--Citron and orange trees, _Hoya carnosa_, _Aucuba
japonica_, _Clianthus puniceus_, etc., etc. _Bryophyllum calicinum_,
_Rochea falcata_, and _Echeveria_. I also learn that the following
plants, among others, produce buds from their foliage
leaves:--_Cardamine pratensis_, _Nasturtium officinale_, _Roripa
palustris_, _Brassica oleracea_, _Arabis pumila_, _Chelidonium
majus_, _Nymphæa guianensis_, _Episcia bicolor_, _Chirita sivensis_,
_Pinguicula Backeri_, _Allium_, _Gagea_, _Tolmia_, _Fritillaria_,
_Ornithogalum_, etc. In _Cardamine_ and several others, a complete
miniature plant is at once produced; in other cases bulbils or
similar detachable buds.

[31] Among various examples I have observed, the most remarkable were
among Foxgloves, growing in great numbers and of large size, in a
wood between Whatstandwell Bridge and Crich, in Derbyshire. In one
case the lowest flower on the stem contained, in place of a pistil, a
shoot or spike of flower-buds, similar in structure to the
embryo-buds of the main spike. I counted seventeen buds on it; of
which the first had three stamens, but was otherwise normal; the
second had three; the third, four; the fourth, four; &c. Another
plant, having more varied monstrosities, evinced excess of nutrition
with equal clearness. The following are the notes I took of its
structure:--1st, or lowest flower on the stem, very large; calyx
containing eight divisions, one partly transformed into a corolla,
and another transformed into a small bud with bract (this bud
consisted of a five-cleft calyx, four sessile anthers, a pistil, and
a rudimentary corolla); the corolla of the main flower, which was
complete, contained six stamens, three of them bearing anthers, two
others being flattened and coloured, and one rudimentary; there was
no pistil but, _in place of it_, a large bud, consisting of a
three-cleft calyx of which two divisions were tinted at the ends, an
imperfect corolla marked internally with the usual purple spots and
hairs, three anthers sessile on this mal-formed corolla, a pistil, a
seed vessel with ovules, and, growing to it, another bud of which the
structure was indistinct. 2nd flower, large; calyx of seven
divisions, one being transformed into a bud with bract, but much
smaller than the other; corolla large but cleft along the top; six
stamens with anthers, pistil, and seed-vessel. 3rd flower, large;
six-cleft calyx, cleft corolla, with six stamens, pistil, and
seed-vessel, with a second pistil half unfolded at its apex. 4th
flower, large; divided along the top, six stamens. 5th flower, large;
corolla divided into three parts, six stamens. 6th flower, large;
corolla cleft, calyx six cleft, the rest of the flower normal. 7th,
and all succeeding flowers, normal.

While this chapter is under revision, another noteworthy illustration
has been furnished to me by a wall-trained pear tree which was
covered in the spring by luxuriant "foreright" shoots. As I learned
from the gardener, it was pruned just as the fruit was setting. A
large excess of sap was thus thrown into other branches, with the
result that in a number of them the young pears were made monstrous
by reversion. In some cases, instead of the dried up sepals at the
top of the pear, there were produced good sized leaves; and in other
cases the seed-bearing core of the pear was transformed into a growth
which protruded through the top of the pear in the shape of a new
shoot.

[32] In partial verification, Mr. Tansley writes:--"Prof. Klebs of Basel
has shown that in _Hydrodictyon_, gametes can only be produced by the
cells of a net when these are above a certain size and age; and then
only under conditions unfavourable to growth, such as a feeble light
or poverty of nutritive inorganic salts or absence of oxygen, or a
low temperature in the water containing the plant. The presence of
organic substances, especially sugar, also acts as a stimulus to the
formation of gametes, and this is also the case in _Vaucheria_. Many
other _Algæ_ produce gametes mainly at the end of the vegetative
season, when food is certainly difficult to obtain in their natural
habitat, and we may well suppose that their assimilative power is
waning. Where, however, as is the case in _Vaucheria_, the plant
depends for propagation mainly on the production of fertilized eggs,
we find the sexual organs often produced in conditions very
favourable to vegetative growth, in opposition to those cases such as
_Hydrodictyon_, where the chief means of propagation is by zoospores.
So that side by side with, and to some extent obscuring, the
principle developed above we have a clear adaptation of the
production of reproductive cells to the special circumstances of the
case."

[33] This establishment by survival of the fittest of reproductive
processes adapted to variable conditions, is indirectly elucidated by
the habits of salmon. As salmon thrive in the sea and fall out of
condition in fresh water (having during their sea-life not exercised
the art of catching fresh-water prey), the implication is that the
species would profit if all individuals ran up the rivers just before
spawning time in November. Why then do most of them run up during
many preceding months? Contemplation of the difficulties which lie in
the way to the spawning grounds, will, I think, suggest an
explanation. There are falls to be leaped and shallow rapids to be
ascended. These obstacles cannot be surmounted when the river is low.
A fish which starts early in the season has more chances of getting
up the falls and the rapids than one which starts later; and, out of
condition as it will be, may spawn, though not well. On the other
hand, one which starts in October, if floods occur appropriately, may
reach the upper waters and then spawn to great advantage; but in the
absence of adequate rains it may fail altogether to reach the
spawning grounds. Hence the species profits by an irregularity of
habits adapted to meet irregular contingencies.

[34] I owe to Mr. (now Sir John) Lubbock an important confirmation of this
view. After stating his belief that between Crustaceans and Insects
there exists a physiological relation analogous to that which exists
between water vertebrata and land-vertebrata, he pointed out to me
that while among Insects there is a definite limit of growth, and an
accompanying definite commencement of reproduction, among
Crustaceans, where growth has no definite limit, there is no definite
relation between the commencement of reproduction and the decrease or
arrest of growth.

[35] While this chapter is passing through the press, I learn from Mr.
White Cooper, that not only are near sight, long sight, dull sight,
and squinting, hereditary; but that a peculiarity of vision confined
to one eye is frequently transmitted: re-appearing in the same eye in
offspring.

[36] An instance here occurs of the way in which those who are averse to a
conclusion will assign the most flimsy reasons for rejecting it.
Rather than admit that the eyes of these creatures living in darkness
have disappeared from lack of use, some contend that such creatures
would be liable to have their eyes injured by collisions with
objects, and that therefore natural selection would favour those
individuals in which the eyes had somewhat diminished and were least
liable to injury: the implication being that the immunity from the
inflammations due to injuries would be so important a factor in life
as to cause survival. And this is argued in presence of the fact that
one of the most conspicuous among these blind cave-animals is a
cray-fish, and that the cray-fish in its natural habitat is in the
habit of burrowing in the banks of rivers holes a foot or more deep,
and has its eyes exposed to all those possible blows and frictions
which the burrowing involves!

[37] In addition to the numerous illustrations given by Mr. Sedgwick, here
is one which Colonel A. T. Fraser published in _Nature_ for Nov. 9,
1893, concerning two Hindoo dwarfs:--"In speech and intelligence the
dwarfs were indistinguishable from ordinary natives of India. From an
interrogation of one of them, it appeared that he belonged to a
family all the male members of which have been dwarfs for several
generations. They marry ordinary native girls, and the female
children grow up like those of other people. The males, however,
though they develop at the normal rate until they reach the age of
six, then cease to grow, and become dwarfs."

[38] This remarkable case appears to militate against the conclusion,
drawn a few pages back, that the increase of a peculiarity by
coincidence of "spontaneous variations" in successive generations, is
very improbable; and that the special superiorities of musical
composers cannot have thus arisen. The reply is that the extreme
frequency of the occurrence among so narrow a class as that of
musical composers, forbids the interpretation thus suggested.

[39] I omitted to name here a cause which may be still more potent in
producing irregularity in the results of cousin-marriages. So far as
I can learn, no attempt has been made to distinguish between such
results as arise when the related parents from whom the cousins
descend are of the same sex and those which arise when they are of
different sexes. In the one case two sisters have children who
intermarry; and in the other case a brother and a sister have
children who intermarry. The marriages of cousins in these two cases
may be quite dissimilar in their results. If there is a tendency to
limitation of heredity by sex--if daughters usually inherit more from
the mother than sons do, while sons inherit more from the father than
from the mother, then two sisters will on the average of cases be
more alike in constitution than a sister and a brother. Consequently
the descendants of two sisters will differ less in their
constitutions than the descendants of a brother and a sister; and
marriage in the first case will be more likely to prove injurious
from absence of dissimilarity in the physiological units than
marriage in the second. My own small circle of friends furnishes
evidence tending to verify this conclusion. In one instance two
cousins who intermarried are children of two sisters, and they have
no offspring. In another the cousins who intermarried are children of
two brothers, and they have no offspring. In the third case the
cousins were descendants of two brothers and only one child resulted.

[40] _A propos_ of this sentence one of my critics writes:--"I cannot find
in this book the statement as first made that the 'life of an
individual is maintained by the unequal and ever-varying actions of
incident forces on its different parts.' Recent physiological work
offers a startling example of the statement."

To the question contained in the first sentence the answer is that I
have not made the statement in the above words, but that it is
implied in the chapter entitled "The Degree of Life varies as the
Degree of Correspondence," and more especially in § 36, which,
towards its close, definitely involves the statement. The verifying
evidence my critic gives me is this:--

"Prof. Sherrington has shown that if the sensory roots of the spinal
nerves are cut one by one there is at first no general effect
produced. That is to say, the remainder of the nervous system
continues to function as before. This condition (lack of general
effect) persists until about six pairs have been cut. With the
severance of the seventh pair, however, the whole central nervous
system ceases to function, so that stimulation of intact sensory
nerves produces no reflex action. After a variable period, but one of
many hours duration, the power of functioning is recovered. That is
to say, if the sensory impulses (from the skin, &c.) reaching the
central nervous system are rapidly reduced in amount, there comes a
point where those remaining do not suffice to keep the structure
'awake.' After a time, however, it adjusts itself to work with the
diminished supply. Similarly Strumpell describes the case of a boy
'whose sensory inlets were all paralyzed except one eye and one ear.'
When these were closed he instantly fell asleep."

[41] Fifty years before the discovery of the Röntgen rays and those
habitually emanating from uranium, it had been observed by Moser that
under certain conditions the surfaces of metals receive permanent
impressions from appropriate objects placed upon them. Such facts
show that the molecules of substances propagate in all directions
special ethereal undulations determined by their special
constitutions.

[42] This classification, and the three which follow it, I quote
(abridging some of them) from Prof. Agassiz's "Essay on
Classification."

[43] For explanations, see "Illogical Geology," _Essays_, Vol. I. How much
we may be misled by assuming that because the remains of creatures of
high types have not been found in early strata, such creatures did
not exist when those strata were formed, has recently (1897) been
shown by the discovery of a fossil Sea-cow in the lower Miocene of
Hesse-Darmstadt. The skeleton of this creature proves that it
differed from such Sirenian mammals as the existing Manatee only in
very small particulars: further dwindling of disused parts being an
evident cause. The same is true as regards, now, we consider that
since the beginning of Miocene days this aberrant type of mammal has
not much increased its divergence from the ordinary mammalian type;
if we then consider how long it must have taken for this large
aquatic mammal (some eight or ten feet long) to be derived by
modification from a land-mammal; and if then we contemplate the
probable length of the period required for the evolution of that
land-mammal out of a pre-mammalian type; we seem carried back in
thought to a time preceding any of our geologic records. We are shown
that the process of organic evolution has most likely been far slower
than is commonly supposed.

[44] Since this passage was written, in 1863, there has come to light much
more striking evidence of change from a more generalized to a less
generalized type during geologic time. In a lecture delivered by him
in 1876, Prof. Huxley gave an account of the successive modifications
of skeletal structure in animals allied to the horse. Beginning with
the _Orohippus_ of the Eocene formation, which had four complete toes
on the front limb and three toes on the hind limb, he pointed out the
successive steps by which in the _Mesohippus_, _Miohippus_,
_Protohippus_, and _Pliohippus_, there was a gradual approach to the
existing horse.

[45] Several of the arguments used in this chapter and in that which
follows it, formed parts of an essay on "The Development Hypothesis,"
originally published in 1852.

[46] _Studies from the Morphological Laboratory in the University of
Cambridge_, vol. vi, p. 84.

[47] _Ibid._, p. 81.

[48] _Studies from the Morphological Laboratory in the University of
Cambridge_, vol. vi, p. 89.

[49] Early in our friendship (about 1855) Prof. Huxley expressed to me his
conviction that all the higher articulate animals have twenty
segments or somites. That he adhered to this view in 1880, when his
work on _The Crayfish_ was published, is shown by his analysis there
given of the twenty segments existing in this fluviatile crustacean;
and adhesion to it had been previously shown in 1877, when his work
on _The Anatomy of Invertebrated Animals_ was published. On p. 398 of
that work he writes:--"In the abdomen there are, at most, eleven
somites, none of which, in the adult, bear ambulatory limbs. Thus,
assuming the existence of six somites in the head, the normal number
of somites in the body of insects will be twenty, as in the higher
_Crustacea_ and _Arachnida_." To this passage, however, he puts the
note:--"It is open to question whether the podical plates represent a
somite; and therefore it must be recollected that the total number of
somites, the existence of which can be actually demonstrated in
insects, is only seventeen, viz., four for the head, three for the
thorax, and ten for the abdomen." I have changed the number twenty,
which in the original edition occurred in the text, to the number
seventeen in deference to suggestions made to me; though I find in
Dr. Sharp's careful and elaborate work on the _Insecta_, that
Viallanes and Cholodkovsky agree with Huxley in believing that there
are six somites in the insect-head. The existence of a doubt on this
point, however, does not essentially affect the argument, since there
is agreement among morphologists respecting the _constancy_ of the
total number of somites in insects.

[50] To avoid circumlocution I let these words stand, though they are not
truly descriptive; for the prosperity of imported species is largely,
if not mainly, caused by the absence of those natural enemies which
kept them down at home.

[51] While these pages are passing through the press (in 1864), Dr. Hooker
has obliged me by pointing out that "plants afford many excellent
examples" of analogous transitions. He says that among true "water
plants," there are found, in the same species, varieties which have
some leaves submerged and some floating; other varieties in which
they are all floating; and other varieties in which they are all
submerged. Further, that many plants characterized by floating
leaves, and which have all their leaves floating when they grow in
deeper water, are found with partly aerial leaves when they grow in
shallower water; and that elsewhere they occur in almost dry soil
with all their leaves aerial.

[52] It will be seen that the argument naturally leads up to this
expression--Survival of the Fittest--which was here used for the
first time. Two years later (July, 1866) Mr. A. R. Wallace wrote to
Mr. Darwin contending that it should be substituted for the
expression "Natural Selection." Mr. Darwin demurred to this proposal.
Among reasons for retaining his own expression he said that I had
myself, in many cases, preferred it--"continually using the words
Natural Selection." (_Life and Letters_, &c., vol. III, pp. 45-6.)
Mr. Darwin was quite right in his statement, but not right in the
motive he ascribed to me. My reason for frequently using the phrase
"Natural Selection," after the date at which the phrase "Survival of
the Fittest" was first used above, was that disuse of Mr. Darwin's
phrase would have seemed like an endeavour to keep out of sight my
own indebtedness to him, and the indebtedness of the world at large.
The implied feeling has led me ever since to use the expressions
Natural Selection and Survival of the Fittest with something like
equal frequency.

[53] I am indebted to Mr. [now Sir W.] Flower for the opportunity of
examining the many skulls in the Museum of the College of Surgeons
for verification of this. Unfortunately the absence, in most cases,
of some or many teeth, prevented me from arriving at that specific
result which would have been given by weighing a number of the under
jaws in each race. Simple inspection, however, disclosed a
sufficiently-conspicuous difference. The under jaws of Australians
and Negroes, when collated with those of Englishmen, were visibly
larger, not only relatively but absolutely. One Australian jaw only
seemed about of the same size as an average English jaw; and this
(probably the jaw of a woman), belonging as it did to a smaller
skull, bore a greater ratio to the whole body of which it formed
part, than did an English jaw of the same actual size. In all the
other cases, the under jaws of these inferior races (containing
larger teeth than our own) were _absolutely_ more massive than our
own--often exceeding them in all dimensions; and _relatively_ to
their smaller skeletons were much more massive. Let me add that the
Australian and Negro jaws are thus strongly contrasted, not with all
British jaws, but only with the jaws of the civilized British. An
ancient British skull in the collection possesses a jaw almost or
quite as massive as those of the Australian skulls. All this is in
harmony with the alleged relation between greater size of jaws and
greater action of jaws, involved by the habits of savages.

[In 1891 Mr. F. Howard Collins carefully investigated this matter:
measuring ten Australian, ten Ancient British, and ten recent English
skulls in the College of Surgeons Museum. The result proved an
absolute difference of the kind above indicated, and a far greater
relative difference. To ascertain this last a common standard of
comparison was established--an equal size of skull in all the cases;
and then when the relative masses or cubic sizes of the jaws were
calculated, the result which came out was this:--Australian jaw,
1948; Ancient British jaw, 1135; Recent English jaw, 1030. "Hence,"
in the words of Mr. Collins, "the mass of the Recent English jaw is,
roughly speaking, half that of the Australian relatively to that of
the skull, and a ninth less than that of the Ancient British." He
adds verifying evidence from witnesses who have no hypothesis to
support--members of the Odontological Society. The Vice-President,
Mr. Mummery, remarks of the Australians that "the jaw-bones are
powerfully developed, and large in proportion to the cranium."]

[54] As bearing on the question of the varieties of Man, let me here refer
to a paper on "The Origin of the Human Races" read before the
Anthropological Society, March 1st, 1864, by Mr. Alfred Wallace. In
this paper, Mr. Wallace shows that along with the attainment of that
intelligence implied by the use of implements, clothing, &c., there
arises a tendency for modifications of brain to take the place of
modifications of body: still, however, regarding the natural
selection of spontaneous variations as the cause of the
modifications. But if the foregoing arguments be valid, natural
selection here plays but the secondary part of furthering the
adaptations otherwise caused. It is true that, as Mr. Wallace argues,
and as I have myself briefly indicated (see _Westminster Review_, for
April, 1852, pp. 496-501), the natural selection of races leads to
the survival of the more cerebrally-developed, while the less
cerebrally-developed disappear. But though natural selection acts
freely in the struggle of one society with another; yet, among the
units of each society, its action is so interfered with that there
remains no adequate cause for the acquirement of mental superiority
by one race over another, except the inheritance of
functionally-produced modifications.

[55] _Darwin and after Darwin_, Part II, p. 99.

[56] _Essays upon Heredity_, vol. i, p. 90.

[57] In a letter published by Dr. Romanes in _Nature_, for April 26, 1894,
he alleges three reasons why "as soon as selection is withdrawn from
an organ the _minus_ variations of that organ outnumber the _plus_
variations." The first is that "the survival-mean must descend to the
birth-mean." The interpretation of this is that if the members of a
species are on the average born with an organ of the required size,
and if they are exposed to natural selection, then those in which the
organ is relatively small will some of them die, and consequently the
mean size of the organ at adult age will be greater than at birth.
Contrariwise, if the organ becomes useless and natural selection does
not operate on it, this difference between the birth-mean and the
survival-mean disappears. Now here, again, the _plus_ variations and
their effects are ignored. Supposing the organ to be useful, it is
tacitly assumed that while _minus_ variations are injurious, _plus_
variations are not injurious. This is untrue. Superfluous size of an
organ implies several evils:--Its original cost is greater than
requisite, and other organs suffer; the continuous cost of its
nutrition is unduly great, involving further injury; it adds
needlessly to the weight carried and so again is detrimental; and
there is in some cases yet a further mischief--it is in the way.
Clearly, then, those in which _plus_ variations of the organ have
occurred are likely to be killed off as well as those in which
_minus_ variations have occurred; and hence there is no proof that
the survival-mean will exceed the birth-mean. Moreover the assumption
has a fatal implication. To say that the survival-mean of an organ is
greater than the birth-mean is to say that the organ is greater _in
proportion to other organs_ than it was at birth. What happens if
instead of one organ we consider all the organs? If the survival-mean
of a particular organ is greater than its birth-mean, the survival
mean of each other organ must also be greater. Thus the proposition
is that every organ has become larger in relation to every other
organ!--a marvellous proposition. I need only add that Dr. Romanes'
inferences with respect to the two other causes--atavism and failing
heredity--are similarly vitiated by ignoring the plus variations and
their effects.

[58] _Westminster Review_, January, 1860. See also _Essays, &c._, vol. i,
p. 290.

[59] "On Orthogenesis and the Impotence of Natural Selection in
Species-Formation," pp. 2, 19, 22, 24.

[60] Address to Plymouth Institution, at opening of Session 1895-6.

[61] _Westminster Review_, April, 1857. "Progress: its Law and Cause." See
also _Essays_, vol. i.

[62] It may be needful to remark, that by the proposed expression it is
intended to define--not Life in its essence; but, Life as manifested
to us--not Life as a _noumenon_: but, Life as a _phenomenon_. The
ultimate mystery is as great as ever: seeing that there remains
unsolved the question--What _determines_ the co-ordination of
actions?

[63] _Prin. of Phys._, 2nd edit., p. 77.

[64] _Ibid._, 3rd edit., p 249.

[65] _Ibid._, p. 124.

[66] Agassiz and Gould, p. 274.

[67] _Prin. of Phys._, 3rd edit., p. 964.

[68] "Parthenogenesis," p. 8.

[69] _Prin. of Phys._, p. 92.

[70] _Ibid._, p. 93.

[71] _Ibid._, p. 917.

[72] "A General Outline of the Animal Kingdom." By Prof. T. R. Jones, F.
G. S., p. 61.

[73] Carpenter.

[74] _Prin. of Phys._, p. 873.

[75] _Ibid._, p. 203.

[76] _Ibid._, p. 209.

[77] _Ibid._, p. 249.

[78] _Ibid._, p. 249.

[79] _Ibid._, p. 250.

[80] _Prin. of Phys._, p. 256.

[81] _Ibid._, p. 212.

[82] _Ibid._, p. 266.

[83] _Prin. of. Phys._, p. 267.

[84] _Ibid._, p. 276.

[85] _Ibid._, 2nd edit., p. 115.

[86] _Prin. of Phys._, p. 954.

[87] _Ibid._, p. 958.

[88] _Ibid._, p. 688.

[89] _Ibid._, p. 958.

[90] "A General Outline of the Animal Kingdom." By Professor T. R. Jones,
p. 61.

[91] _Prin. of Phys._, p. 907.

[92] Should it be objected that in the higher plants the sperm-cell and
germ-cell differ, though no distinct co-ordinating system exists, it
is replied that there _is_ co-ordination of actions, though of a
feeble kind, and that there must be some agency by which this is
carried on.

[93] It is a significant fact that amongst the dioecious invertebrata,
where the nutritive system greatly exceeds the other systems in
development, the female is commonly the largest, and often greatly
so. In some of the Rotifera the male has no nutritive system at all.
See _Prin. of Phys._, p. 954.

[94] _Prin. of Phys._, p. 908.

[95] "Parthenogenesis," pp. 66, 67.

[96] "Lectures on Animal Chemistry." By Dr. Bence Jones. _Medical
Times_, Sept. 13th, 1851. See also _Prin. of Phys._, p. 171.

[97] _Cyclopædia of Anatomy and Physiology_, Vol. IV, p. 506.

[98] From a remark of Drs. Wagner and Leuckart this chemical evidence
seems to have already suggested the idea that the sperm-cell becomes
"metamorphosed into the central parts of the nervous system." But
though they reject this assumption, and though the experiments of Mr.
Newport clearly render it untenable, yet none of the facts latterly
brought to light conflict with the hypothesis that the sperm-cell
contains unorganized co-ordinating matter.

[99] Quain's _Elements of Anatomy_, p. 672.

[100] The maximum weight of the horse's brain is 1 lb. 7 ozs.; the human
brain weighs 3 lbs., and occasionally as much as 4 lbs.; the brain of
a whale, 75 feet long, weighed 5 lbs. 5 ozs.; and the elephant's
brain reaches from 8 lbs. to 10 lbs. Of the whale's fertility we know
nothing; but the elephant's quite agrees with the hypothesis. The
elephant does not attain its full size until it is thirty years old,
from which we may infer that it arrives at a reproductive age later
than man does; its period of gestation is two years, and it produces
one at a birth. Evidently, therefore, it is much less prolific than
man. See Müller's _Physiology_ (Baly's translation), p. 815, and
Quain's _Elements of Anatomy_, p. 671.

[101] That the size of the nervous system is the measure of the ability to
maintain life, is a proposition that must, however, be taken with
some qualifications. The ratio between the amounts of gray and white
matter present in each case is probably a circumstance of moment.
Moreover, the temperature of the blood may have a modifying
influence; seeing that small nervous centres exposed to rapid
oxidation will be equivalent to larger ones more slowly oxidized.
Indeed, we see amongst mankind, that though, in the main, size of
brain determines mental power, yet temperament exercises some
control. There is reason to think, too, that certain kinds of nervous
action involve greater consumption of nervous tissue than others; and
this will somewhat complicate the comparisons. Nevertheless, these
admissions do not affect the generalization as a whole, but merely
prepare us to meet with minor irregularities.

[102] Let me here note in passing a highly significant implication. The
development of nervous structures which in such cases take place,
cannot be limited to the finger-ends. If we figure to ourselves the
separate sensitive areas which severally yield independent feelings,
as constituting a network (not, indeed, a network sharply marked out,
but probably one such that the ultimate fibrils in each area intrude
more or less into adjacent areas, so that the separations are
indefinite), it is manifest that when, with exercise, the structure
has become further elaborated, and the meshes of the network smaller,
there must be a multiplication of fibres communicating with the
central nervous system. If two adjacent areas were supplied by
branches of one fibre, the touching of either would yield to
consciousness the same sensation: there could be no discrimination
between points touching the two. That there may be discrimination,
there must be a distinct connection between each area and the tract
of grey matter which receives the impressions. Nay more, there must
be, in this central recipient-tract, an added number of the separate
elements which, by their excitements, yield separate feelings. So
that this increased power of tactual discrimination implies a
peripheral development, a multiplication of fibres in the
trunk-nerve, and a complication of the nerve-centre. It can scarcely
be doubted that analogous changes occur under analogous conditions
throughout all parts of the nervous system--not in its sensory
appliances only, but in all its higher co-ordinating appliances, up
to the highest.

[103] _Essays upon Heredity_, p. 87.

[104] _Les Maladies des Vers à soie_, par L. Pasteur, Vol. I, p. 39.

[105] Curiously enough, Weismann refers to, and recognizes, syphilitic
infection of the reproductive cells. Dealing with Brown-Séquard's
cases of inherited epilepsy (concerning which, let me say, that I do
not commit myself to any derived conclusions), he says:--"In the case
of epilepsy, at any rate, it is easy to imagine [many of Weismann's
arguments are based on things 'it is easy to imagine'] that the
passage of some specific organism through the reproductive cells may
take place, as in the case of syphilis" (p. 82). Here is a sample of
his reasoning. It is well known that epilepsy is frequently caused by
some peripheral irritation (even by the lodging of a small foreign
body under the skin), and that, among peripheral irritations causing
it, imperfect healing is one. Yet though, in Brown-Séquard's cases, a
peripheral irritation caused in the parent by local injury was the
apparent origin, Weismann chooses gratuitously to assume that the
progeny were infected by "some specific organism," which produced the
epilepsy! And then though the epileptic virus, like the syphilitic
virus, makes itself at home in the egg, the parental protoplasm is
not admitted!

[106] _Philosophical Transactions of the Royal Society for the Year 1821_,