[DX]Darwin, "Animals and Plants under Domestication," vol. i. p. 104.

[DY]Similarly, from a chance sport of a one-eared rabbit, Anderson formed a breed which steadily produced one-eared rabbits ("Animals and Plants under Domestication," vol. i. p. 456). This is an example of asymmetrical variation. Variations are generally, but not always, symmetrical. Superficial colour-variations are sometimes asymmetrical. Gasteropod molluscs are nearly always asymmetrically developed. Among insects, Anisognathus affords an example of the asymmetrical development of the mandible. Our right-handedness is a mark of asymmetry.

[DZ]"Natural Inheritance," p. 32.

[EA]See "Animals and Plants under Domestication," vol. ii. p. 40, from which illustrations are taken.

[EB]"Evolution and Disease," p. 169.

[EC]"Animals and Plants under Domestication," vol. ii. p. 8.

[ED]"Darwinism," p. 107.

[EE]Darwin, "Animals and Plants under Domestication," vol. ii. pp. 17, 18.

[EF]"Animals and Plants under Domestication," vol. ii. p. 201.

[EG]Ibid. p. 282. The phenomena of the seasonal dimorphism of butterflies and moths show that changes of temperature (and perhaps moisture, etc.) determine very striking differences in these insects.

[EH]"Animals and Plants under Domestication," vol. ii. p. 244.

[EI]"Darwinism," p. 293.

[EJ]"Evolution of Sex," p. 22.

[EK]"Incidental Observations in Pedigree Moth-breeding," F. Merrifield. Transactions Entomological Society, 1889, pt. i. p. 79, et seq.

[EL]Nature, vol. xli. p. 393.

[EM]See Professor Meldola's edition of Professor Weismann's "Studies in the Theory of Descent," and Mr. Cunningham's translation of Professor Eimer's "Organic Evolution."

[EN]See Darwin, "Animals and Plants under Domestication," vol. ii. p. 252.

[EO]See abstract in Nature, vol. xxxiv. p. 515.

[EP]See Nature, vol. xxxvii. p. 557.

[EQ]"Sense-Organs and Perception of Fishes:" Journal of Marine Biological Association, New Series, vol. i. No. 3, p. 225.

[ER]Nature, vol. xlii. p. 201.

[ES]Nature, vol. xxxvi. p. 273.

[ET]Journal of Marine Biological Association, New Series, vol. i. No. 3, p. 235.

[EU]Mr. S. Klein mentions a similar fact in connection with Bombyx quercus (Nature, vol. xxxv. p. 282).

[EV]Journal of Marine Biological Association, New Series, vol. i. No. 2, p. 211.

[EW]A friend of mine informs me that his limit is about 17,500 per second, 20,000 being quite inaudible.

[EX]Journal of Marine Biological Association, New Series, vol. i. No. 3, p. 251.

[EY]Of course, anglers will say that what may be true for pollack and other coarse and vulgar sea-fish does not apply to King Salmon or Prince Trout.

[EZ]"Senses of Animals," p. 117.

[FA]See a very interesting and lucid paper by Professor Crum Brown, whose name is intimately connected with this subject, in Nature, vol. xl. p. 449.

[FB]It is interesting to note that in the blind-fish (Amblyopsis spelæus) the semicircular canals are, according to Wyman, unusually large.

[FC]The dampers must, of course, be lifted by depressing the loud pedal.

[FD]"Special Physiology," p. 636.

[FE]A band and not a line, because R. is unstable to the impact of a considerable range of light-vibrations.

[FF]Mr. Chattock has kindly supplied me with the following note:—

"Readings at the violet end were taken at the extremity of the lavender rays, at the point where the faint band of lavender light seemed to end off about half-way across the field of view (the cross-wires being invisible).

"At the red end the cross-wires were always visible, and were in each case set to the point where the top horizontal edge of the spectrum lost its definition.

"Other things equal, the 'red' readings should be more reliable than the violet, therefore, from the greater definiteness of the point observed, and the means of observing it. But against this has to be set off the fact that the extreme violet rays were spread out by the prism used more than eight times as much as the red rays.

"In any case, the wide differences observed in the 'red' readings are much greater than could have been due to misunderstanding or careless observation—as shown by setting the instrument to maximum and minimum readings, and noting the very obvious difference between them apparent to a normal eye. The same conclusion is rather borne out by the closer (average) agreement between the two eyes of the same individual than between those of different persons.

"The source of light was the central portion of an ordinary Argand burner."

[FG]The variations above indicated throw light on a fact to which Lord Rayleigh has directed attention. The yellow of the spectrum may be matched by a blending of spectral red and spectral green; but the proportions in which these spectral colours must be mixed differ for different individuals. The complementary colours for different individuals are also not precisely the same.

[FH]"Colour-Vision and Colour-Blindness," R. Brudenell Carter (Nature, vol. xlii. p. 56).

[FI]Journal of Marine Biological Association, New Series, vol. i. Nos. 2 and 3. His experiments with regard to the colour-sense in fishes gave, for the most part, negative results.

[FJ]We must remember how largely the antennæ are used when an insect is finding its way about. Watch, for example, a wasp as it climbs over your plate. If the antennæ be removed, it seems to stumble about blindly. The antennæ seem almost to take the place of eyes at close quarters.

[FK]"Senses of Animals," p. 194.

[FL]See Nature, vol. xli. p. 407.

[FM]Chap. x. p. 202.

[FN]The observations are not yet published, and I have to thank Lord Rayleigh for his courtesy in allowing me to make use of this fact.

[FO]Professor Langley finds that the maximum effect with a radiating

We are sensitive to radiations from a body at 100° C. But when the temperature falls below the normal temperature of the body we are not sensitive to heat-vibrations, but to loss of heat from the surface exposed. The limit of sensibility to heat-vibrations, therefore, probably lies between 7.5 and 11 thousandths of a millimetre. I have taken about 9.25 as the limit.

[FP]I use this term in a broad sense, as the process involved in the formation of what I shall term constructs.

[FQ]And I may add it is not an easy matter to explain to those who have not considered such questions. It is a matter of the correlation of the testimony of the sense-organs. A boy stands before me. I go to him and touch him, and pass my hands downwards from head to foot. Then I stand a little way off and look at him. His image on my retina is inverted. But as I run my eye over him I direct my eye downwards to his feet and upwards to his head. I am not conscious that the stimuli are running upwards along the retinal image. Thus my eye-muscles and my other muscular and tactile sensations seem to tell me that he is one way upwards. The image on my retina tells me, though I am not conscious of the fact, that he is the other way upwards. But he cannot be both! The testimony of one sense has to give way. One standard or the other has to be adopted. Practically that of touch and the muscular sensations is unconsciously selected, and sight-sensations are habitually interpreted in terms of this standard. So long as the two are sufficiently accurately correlated, the practical requirements of the case are met. And it is well known that it is not difficult, with a little practice, to establish a new correlation. This is indeed done every day by the microscopist, for whom the images are all reversed by his instrument. He very soon learns, however, that to move the object, as seen, to the left, he must push it to the right. A new correlation is rapidly and correctly established.

[FR]I use this term because the word "percept" is used in different senses by different writers, e.g. by Mr. Mivart and Mr. Romanes.

[FS]"Let the perception be considered to be made up of x + y; x being the ego, or self, and y the object. The mind has the power of supplying its own - x, and so we get (through the imagination of the mind and the object) x + y - x, or y pure and simple" (Mivart, "On Truth," p. 135). Mr. Mivart devotes a whole section of this work to the defence of ordinary common-sense realism. The above assertion seems to contain the essence of his teaching in the matter.

[FT]If it be said that the object does exist independently of man, though not in the phenomenal guise under which we know it, I would reply—Not so; for it is to the existence under this phenomenal guise that we apply the word "object." In philosophical language, the existence, stripped of its phenomenal aspect, is called the Ding an sich. Its essential character is its independence of man; and hence its unknowability.

[FU]I avoid, for the present, the use of the terms "abstraction" and "abstract idea" because they are employed in different senses by different authors.

[FV]"Outlines of Psychology," p. 153.

[FW]Ibid. p. 339.

[FX]"Science of Thought," p. 453.

[FY]For compound or generic ideas "not consciously fixed and signed by means of an abstract name," Mr. Romanes ("Mental Evolution in Man," p. 36) has suggested the term "recept." In the photographic psychology which he adopts, the percept is an individual and particular photograph, the recept a generalized or composite photograph. "The word 'recept,'" he says, "is seen to be appropriate to the class of ideas in question, because, in receiving such ideas, the mind is passive." This, it will be observed, is in opposition to the teaching of this chapter, in which the activity of the mind in perception has been insisted on. Mr. Romanes's recepts answer in part to what I have termed constructs, which, as we have seen, are, as a rule, from the first general rather than particular, and in part to concepts reached through analysis. Mr. Romanes, for example, speaks of ideas of principles (e.g. the principle of the screw) and ideas of qualities (e.g. good-for-eating and not-good-for-eating) as recepts (p. 60). On the other hand, Mr. Mivart ("The Origin of Human Reason," p. 59; see also his work "On Truth") terms such generic affections "sensuous universals." It may be well to append Mr. Romanes's and Mr. Mivart's tabular statements.

In Mr. Mivart's terminology, the representations of the lower group are "mental images" or "phantasmata." The term "consciousness" is by him restricted to the higher region of ideas, the term "consentience" being applied to the faculty by which cognitive affections are felt, unified, and grouped without consciousness. There is a difference in kind, according to Mr. Mivart, between "consentience" and "consciousness;" and the former could therefore never develop into the latter, nor the latter be evolved from the former. For this reason (because of the philosophy it is intended to carry with it) I shall not employ the word "consentience," which would otherwise be a useful term.

[FZ]We do not speak of the filling in the complement of a percept (the construction of the object at the bidding of a simple impression) as a matter of conscious inference. I do not consciously infer that yonder moss-rose is scented. Scent is an integral part of the construct. From the appearance of the rose, I may, however, infer that a rose-chafer has disturbed its petals. The complement of the percept, if inferred at all, is unconsciously inferred.

[GA]"Outlines of Psychology," p. 392.

[GB]"Outlines of Psychology," p. 414.

[GC]Mr. Romanes adopts a different use of the terms "reason" and "rational," to which allusion will be made in the next chapter.

[GD]"Chapters on Animals," p. 9.

[GE]Or perhaps we may say, in the language of analogy, that when the germinal psychoplasm of some dim form of organic memory is fertilized by the union therewith of the more active male element of discrimination, a process of segmentation of the psychoplasm sets in by which, in process of differentiation, the tissues and organs of the mind are eventually developed.

[GF]Nature, vol. xxxviii. p. 257.

[GG]For examples, see Romanes's "Animal Intelligence," p. 455.

[GH]I use the word "arbitrary" in the sense that they form no part of the normal construct such as would be formed by the animal.

[GI]"The Senses of Animals," p. 277.

[GJ]As I understand the observations here tabulated, the twelve cards lay always within Van's reach and sight. An ordinary untrained dog would have taken no notice of them. But Van, when he wanted food or tea, went and fetched the appropriate card, and got what he wanted in exchange. In twelve days he only made two mistakes, bringing "Nought" once and "Door" once.

[GK]"Mental Evolution in Man," p. 27.

[GL]"Intelligence of Animals," p. 121.

[GM]Mr. Romanes also says ("Mental Evolution in Animals," p. 235), "This abstract idea of ownership is well developed in many if not in most dogs." By an abstract idea of ownership I understand a conception of ownership which, to modify Mr. Romanes's phrase, is quite apart from any objects or persons of which such ownership happens to be characteristic. Even if we believe that a dog can regard this or that man as his owner, or this or that object as his master's property, still even this seems to me a very different thing from his possessing an abstract idea of ownership.

[GN]Doubt has recently been thrown on this fact. Mr. Bateson has shown that some fishes do not hear well, and has suggested that the carp may be attracted by seeing people come to the edge of the pond.

[GO]Journal of Marine Biological Association, New Series, vol. i. No. 2, p. 214. I should not myself have used the word "explanation."

[GP]Ibid. vol. i. No. 3, p. 240.

[GQ]I have to thank this gentleman for a most interesting account of the intelligence of his favourite bird.

[GR]Professor Max Müller suggests to me that perhaps the ants were frightened.

[GS]"Mental Evolution in Animals," p. 82.

[GT]Ibid. p. 48.

[GU]These fall under the "practical intelligence" of Mr. Mivart. All their intelligent activities, in his view, are performed by the exercise of merely sensitive faculties, through their "consentience." I agree to so large an extent with Mr. Mivart in his estimate of animal intelligence, and in his psychological treatment, that I the more regret our wide divergence when we come to the philosophy of the subject. I am with him in believing that conception and perception, in the sense he uses the words, are beyond the reach of the brute. But I see no reason to suppose that these higher faculties differ in kind from the lower faculties possessed by animals. They differ generically, but not in kind. I believe that, through the aid of language, the higher faculties have been developed and evolved from the lower faculties. Here, therefore, I have to part company from Mr. Mivart.

[GV]Romanes, "Animal Intelligence," p. 401.

[GW]"Animal Intelligence," p. 465.

[GX]"Animal Intelligence," p. 430; and Nature, vol. xix. p. 409.

[GY]"Animal Intelligence," p. 497.

[GZ]Mr. Romanes regards it as, in the case of the capuchin, a recept. But when he speaks of a generic idea of causation, and generic ideas of principles, and of qualities as recepts, I find it exceedingly difficult to follow him. They seem to me to be concepts supposed to be formed in the absence of language.

[HA]Page 54.

[HB]Vol. xx. p. 96.

[HC]Nature, vol. xxi. p. 34.

[HD]Romanes, "Animal Intelligence," p. 17: Definition of reason.

[HE]"Mental Evolution in Animals," p. 318.

[HF]"Lessons from Nature," pp. 226, 227.

[HG]"Physiological Æsthetics:" chapter on "Pleasure and Pain."

[HH]All of these, at any rate, satisfy Mr. Herbert Spencer's definition. Pleasure he describes as a feeling which we seek to bring into consciousness and retain there; pain, as a feeling which we seek to get out of consciousness and keep out.

[HI]"Types of Ethical Theory," vol. ii. p. 350.

[HJ]Such consciousness of activity is probably associated with the innervation of afferent, not efferent, nerves.

[HK]Journal of Marine Biological Association, New Series, vol. i. No. 2, pp. 216, 217.

[HL]"Outlines of Psychology," p. 481.

[HM]Ibid. p. 494.

[HN]Page 70.

[HO]Page 104.

[HP]Nature, vol. xxxvii. p. 619.

[HQ]Vol. i. p. 310, under date 1876.

[HR]"Mental Evolution in Animals," p. 318.

[HS]"Descent of Man," pt. i. chap. iii.

[HT]Miss Nellie Maclagan describes how her Newfoundland similarly took a roll to a hungry pauper-friend (Nature, vol. xxviii. p. 150). Mr. Duncan Stewart gives (Nature, vol. xxviii. p. 31) the case of a cat who used frequently to provide her blind mother with food. Sir Harry Lumsden states that during the cold autumn of 1878 some tame partridges in Aberdeenshire brought two wild coveys to be fed near the doorstep of the house. And a case has been communicated to me by Miss Agnes Tanner, of Clifton, of a thrush that pulled up worms on the lawn for a lame companion.

[HU]"Animal Intelligence," p. 440.

[HV]"Animal Intelligence," p. 442.

[HW]Ibid. p. 444.

[HX]Ibid. p. 451.

[HY]"Animal Intelligence," p. 387.

[HZ]"Animal Intelligence," p. 486.

[IA]Ibid. p. 141.

[IB]"Animal Intelligence," p. 443.

[IC]Mr. Alexander Mackennal, vol. xxi. p. 397.

[ID]"Descent of Man," pt. i. chap. iii., quoted from Brehm's "Thierleben."

[IE]Nature, vol. xxviii. p. 32.

[IF]"Descent of Man," quoted by Romanes, p. 445.

[IG]Nature, vol. xl. p. 327.

[IH]Another example of beauty which can hardly be said to have been evolved for beauty's sake is to be seen in birds' eggs. Mr. Henry Seebohm regards the bright colours of some birds' eggs as a difficulty in the way of the current interpretation of organic nature. "Few eggs," he says (Nature, vol. xxxv. p. 237), "are more gorgeously coloured [than those of the guillemot], and no eggs exhibit such a variety of colour. [They are sometimes of a bluish green, marbled or blotched with full brown or black; sometimes white streaked with brown; sometimes pale green or almost white with only the ghosts of blotches and streaks; and sometimes the reddish brown extends so as to form the ground-tint which is blotched with deeper brown.] It is impossible to suppose that protective selection can have produced colours so conspicuous on the white ledges of chalk cliffs; and sexual selection must have been equally powerless. It would be too ludicrous a suggestion to suppose that a cock guillemot fell in love with a plain-coloured hen because he remembered that last season she laid a gay-coloured egg."

If we connect colour with metabolic changes, its occurrence in association with the products of the highly vascular oviduct will not be surprising. Some guidance is, however, on the principles advocated in Chapter VI., required to maintain a standard of coloration. In many cases such guidance is found in protective selection, as in the plover's eggs in our frontispiece. In the guillemot's egg such protective selection seems to be absent, and, as Mr. Seebohm himself says, "no eggs exhibit such a variety of colour."

In our present connection, however, the point to be noticed is that many eggs are undoubtedly beautiful. But they cannot have been in any way selected for the sake of their beauty.

[II]"Outlines of Psychology," p. 537.

[IJ]I should add, "or as conceptual thought."

[IK]This paragraph is quoted from the author's "Springs of Conduct," p. 263.

[IL]Page 347.

[IM]I have said nothing about the emotions of invertebrates, because I have nothing special to say. They have, no doubt, emotions analogous to fear, anger, and so on. But it is difficult to interpret their actions. The "angry" wasp is, perhaps, a good deal more frightened than furious. Sir John Lubbock's interesting experiments seem to show that ants have what is termed the instinct of play. But this admirable observer has rendered it probable that sympathy and affection in ants and bees have been somewhat exaggerated.

[IN]I use the term "incomplete," and not "imperfect," because Mr. Romanes, in his admirable discussion of the subject, applies the term "imperfect instinct" to cases where the instinct is not perfectly adapted to the end in view (see "Mental Evolution in Animals," p. 167).

[IO]Macmillan's Magazine, February, 1873. Professor Eimer, in his "Organic Evolution" (English translation, p. 245), narrates similar experiences.

[IP]Mr. W. Larden states, in Nature (vol. xlii.), that his brother extracted, from the oviduct of a Vivora de la Cruz snake in the West Indies, two young snakelets six inches long. Both, though thus from their mother's oviduct untimely ripped, threatened to strike, and made the burring noise with the tail, characteristic of the snake.

[IQ]Dr. McCook confirms the observation that the clearings are kept clean, that the ant-rice alone is permitted to grow on them, and that the produce of this crop is carefully harvested; but he thinks that the ant-rice sows itself, and is not actually planted by the ants (see Sir John Lubbock's "Scientific Lectures," 2nd edit., p. 112).