Chapter XXIV: The Building of Reflex Arcs (2)

We are told on high authority that not education but educability is transmissible, and yet this humble reflex appears in very young dogs that could hardly if ever have known the impact of a stone. Incidentally we are compelled to remember how in past battles of our youth the aim both of “ourselves and the enemy” was deplorably poor, and not from want of practice. This school-boy-stone reflex is either an example of educational effects transmitted or of a minute bit of the unpacking of an original complexity which it would require the brain of a de Quincey to work out. But if we suppose the initial stages of such a stimulus as the occasional impact of a stone in many generations to be slowly ingrained in the skin-receptors, reflex-arcs and receptors we do not need opium either for the acceptance of orthodox dogma or to aid us in the Mendelian alternative to a very simple ideal construction.

This digression bears on the initiative of the more important scratch-reflex, and it is profitable to ask “are not both of these reflexes in dogs examples of Evolution of the Indifferent?” Is it possible to imagine that from its inception to its fully-formed state, with a specialised territory of skin-receptors accurately mapped out, with receptor neurones, reflex-arcs and adapted effectors, this scratch-reflex can have arisen through Germinal Selection or selective processes within the germ? At no stage can anything more than a contribution to more or less comfort to the animal be held to result from its operation. It is strangely reminiscent of the proceedings of an elderly man after lunch on a hot day when he protects his head against house-flies with a handkerchief. I am aware that it is but one of a large number of reflexes produced for the purpose of grooming the trunk head or limbs of animals as low down in the scale as the house-fly or grasshopper, many of which were beautifully described a few years ago by Miss Frances Pitt in the _National Review_ in an article dealing with small mammals, chiefly rodents. But I have availed myself here as elsewhere, of the liberty of doing what Professor Sherrington says we may do, and consider this scratch-reflex as split off from the rest of the animal’s behaviour for the purpose of analysis. He also says in discussing the subject of parasites moving across the receptive surface of the skin that the ulterior purpose may be the removal of what “would confuse its function as a receptive surface to more significant environmental stimuli.” This statement is hypothetical and the problem obscure; but at any rate we know this that the removal of the parasite must conduce to the greater comfort of the dog without any more recondite purpose. The one suggested by Professor Sherrington would in some possible but very vague manner be referable to selection, but, whether the suggestion be valid or not, it is almost impossible to suppose that a saddle-shaped area of the kind described could be under the guidance of selection. The law of Parcimony forbids. There is a close similarity between this saddle-shaped area in the dog and that on the cow’s trunk described in Chapter X. It is difficult to believe that from man downwards to grasshoppers relief from mild irritating causes such as this is not enjoyable to the particular animal, and yet indifferent altogether as to its survival in the struggles of life for food and mates. The “scalptor-reflex” only reaches the limits of the receptive field of the scratch-reflex and it is contrary to observed facts that parasites confine their depredations just to the region where the formidable scalptor-reflex can reach. The wicked flea knows better than that. The initiative of this reflex can well be pictured as taking place in domesticated dogs and their wild ancestors whose habitats in prehistoric times were probably infested with these irritants to such a degree that no modern mind can conceive, and the adequate stimuli, leading to receptors after ages of impact and consequent hammering out pathways through certain reflex-arcs until the required weapons of offence or effectors were organised into a _defensive-offensive system_--were there in profusion. But a great and fundamental principle of the evolutionary process such as Selection is not honoured by being dragged in, even for forensic purposes, to account for results which owe to the search for comfort their perfection of organisation. I have personally seen in some professional invalids of the softer sex nearly as perfect adaptations to their comfort which in no way contributed to their length of life. This may be put aside as irrelevant but it is at least suggestive.

I submit the statement as to the scratch-reflex in the dog that from beginning to end it is an _indifferent_ mechanism and the probability is immense that its initial stages were governed alone by repeated stimuli from parasites which produced receptors, conducting fibres afferent neurones and efferent neurones, leading into the Final Common Path controlling the flexors of the hind limb. It would then come under the Law of Subjective or Hedonic Selection formulated by Professor Stout in the words: “Lines of action, if and so far as they are unsuccessful, tend to be discontinued or varied; and those which prove successful to be maintained. There is a constant tending to persist in those movements and motor attitudes which yield satisfactory experiences, and to renew them when similar conditions recur; on the other hand those movements and attitudes which yield unsatisfactory experiences tend to be discontinued at the time of their occurrence, and to be suppressed on subsequent similar occasions.”

In this connection a statement from Professor McDougall’s work may be advantageously quoted. He says that “It is characteristic of those (arcs) of the higher or third level that their organisation, their interconnections, by means of which the simpler neural systems of great complexity, is _congenitally determined in a very partial degree only_, and is principally determined in each individual by the course of its experience. The arcs of the higher level thus constitute the physiological basis or condition of docility, the power of learning by experience.”[88] (My italics)

[88] _Op. cit._ p. 21.

Scratch Reflex of the Cat.

There is a notable difference between the scratch-reflex of the dog and that of the cat, especially as to the site of its receptive-field. That of the dog has been referred to, but it appears to be generally accepted that the cat has no such saddle-shaped or indeed other area of skin receptive-field on its back or flanks. I have repeatedly tried by various mechanical stimuli, applied both irregularly and rhythmically, to evoke a scratch-reflex in a cat, young or adult, on the surface corresponding to that of the dog, and have found no response. This has been tried both when the animal was awake and when asleep. But the receptive field of the cat’s scratch-reflex has received careful and elaborate attention, which is described in a paper by Professor Sherrington in the _Journal of Physiology_, Vol. LI. No. 6. By means of delicate stimuli, mechanical and electrical in a decerebrate cat, the receptive-field of the scratch-reflex has been accurately delineated in the pinna, and several other pure reflexes have been obtained. These are protective of the pinna; some, the retraction and folding reflexes seem directed against irritant touches, _e.g._ the settling of fleas--or against exposure to injury in fighting; others, the cover and head-shake and scratch-reflexes against the ingress of foreign matter, such as dust, water, insects, into the meatus and ampulla. The threshold for their elicitation is extremely low, that is to say, they require very gentle stimuli to evoke them, while with the exception of the scratch-reflex they are elicited with difficulty and uncertainty _by electrical stimuli_ (My italics) to which the animal has been subjected in the course of its total experience. He adds that the pinnal reflexes are readily obtained in the normal animal, and I may allude here to some small observations I made on a normal young cat during profound sleep, recorded in _Nature_, Vol. 106, Sept. 2, 1920. Light mechanical stimuli, applied during this state of deep sleep to the internal surface of the pinna, especially close to the meatus, produced first, twitching of the facial muscles on the same side; second, as this ceased the fore foot was moved irregularly towards the ear, and third, as this ceased a rhythmical scratching action of the hind foot took its place, the rate of which seemed to be exactly the same as that of the scratch-reflex in the dog evoked from stimulation of the flank and back. I had not then, unfortunately read more than an abstract of the above paper, but if the full account be followed it will be seen that the various “territories” belonging to all the former-reflexes are now known as well as the frontiers of a European Kingdom. All I was able to do with this unusual opportunity of a heavy sleep in a normal young cat was to verify more roughly Professor Sherrington’s observations and slightly to extend them _in respect of a sleeping animal_.

In the course of these observations on a young cat I examined the various regions of the back and flanks with mechanical stimuli of different degrees of strength. These were applied during sleep and I found that it was more often during a moderate than a light or deep sleep that the following results were shown--chiefly under the stronger stimuli the tail was raised sharply and swept in a circular way, and this would be repeated according as the stimulus was applied; but at the same time there was shown a strong, irregular twitching along the flank, extending forwards to a point near the level of the shoulder. This latter reflex would appear to be a reaction on the part of the panniculus carnosus. Both the reflex of the muscles of the tail and this of the flanks appear to be connected in their origin with movements of parasites in their respective territories.

In considering the scratch-reflex in the cat a subtle bit of adjustment is found. That coarse and simple scratching of its ear, which we see so often in the cat, must have often astonished us for its vigour and yet its bloodless character. This action is of course a purposeful one, for it goes on when the animal is awake. Here if anywhere this profoundly hedonistic animal shows that for it the laws of comfort are its laws of conduct. It is clear that there may be two processes or conditions involved in its bloodless violence. On the one hand the reflex retractile mechanism of the claws may be kept in abeyance by another reaction which is pre-potent; on the other, it is a fact that the hind foot in the cat is furnished with claws which are much blunter than those of the fore foot. As far as I have been able to examine cats of different ages I have found the claws of the hind foot more like the blunt claws of a dog than the familiar sharp claws of the Felidæ. So in the violent scratching referred to there may be a double reason associated in the process. As to the difference in the sharpness of the fore and hind claws it would appear to be remarkably like a transmitted bit of adaptation initiated and kept in being by use and habit in progression, for the hind foot in such animals as the cat has a larger share in this action than the fore foot. But here it is difficult as so often to assign to selection its possible share of the adjustment.

Certain minor but persistent reflexes may be briefly mentioned in support of this side of the evolutionary process. In the dog and cat, as we know them, the action of the muscles of the tail by which it is elevated during the act of defæcation is very suggestive of a reflex acquired by a very small degree of physical comfort and repeated in countless individuals, wild and domesticated. I have seen not only this but a few small scratches made by a cat before defæcation in a kitten as young as three weeks old. It is also mentioned in illustration of a vestigial character that a horse will paw the ground with no immediate apparent object, the act being derived from ancestors which thus cleared away snow from the ground. This is claimed, doubtfully I think, as a vestige of a formerly _useful_ habit but seems more probably to be one of these indifferent reflexes connected with comfort than with survival-value.

It will be observed that in this branch of the case for Lamarck _v._ Weismann the indirect evidence from inference far exceeds in amount that of direct experimental evidence, but from the nature of the problem under consideration this could not be otherwise.

If we may again look back in thought over the long series of animals, from man downwards, we shall picture those of the spinal level striving (with apologies for the use of an anthropomorphic word) to reach the sensory level and finding out the fact that few there be that enter therein. Again we see in vision the higher creatures of the sensory level reaching forwards to the strait paths of primate existence, and again finding the difficulty of self-advancement that their predecessors found. We see the elect few of these, by a happy combination of nature and nurture, uprearing to glory and honour the primate stock with its culmination in man. A long vista indeed and a vision, but assuredly no mere figment of the imagination, as some of the slender facts and arguments here would seem to show. With Professor Bateson we personify Nature in the story, with her wonted coyness betraying the fact that though she is stern she has her tolerant moods; that she allows her children, even that “insurgent son” who calls himself Homo Sapiens, a genial liberty to frame new reflex-arcs which make for his enjoyment of life in indifferent fields, and _that the great neural process of Facilitation is the leading factor in their constructions and probably also in more deeply-based systems of sensori-motor arcs_.

SUMMARY.

Though it be true that _dolus latet in generalibus_, it is a more important truth that “without premature generalisations the true generalisation would never be arrived at.”[89]

[89] Herbert Spencer, _Essays_, II, 57.

Therefore I conclude:--

1. That Plasto-diēthēsis, or the moulding and sifting processes
experienced by organisms, represents the beginning and end of higher
animal evolution; and that its wide hyphen stands for the provinces
where Mendelism, Mutationism, Tetraplasty, Orthogenesis, and the
dynamical work of growth on Form, as well as other factors yet to be
discovered, can range at large.

2. That personal selection is the leading form of that process in
higher animals, whereas among Invertebrates, especially unicellular
forms, selection of groups is the rule.

3. That Initiative in animal evolution comes by stimulation,
excitation, and response in new conditions, and is followed by
repetition of these phenomena until they result in structural
modifications, transmitted and directed by selection and the laws
of genetics--a series of events which agree with Neo-Lamarckian
principles.

4. That undesigned experiments in the arrangement of the Mammalian
hair, and the production of new bursæ, as well as the designed
experiments of Pawlow, support the foregoing claims, with which agree
the converging facts of--varieties of epidermis, arrangement of the
papillary ridges, flexures of the palm and sole, the formation of the
plantar arch, the origin of certain muscles, the innervation of the
human skin, and the building of reflex-arcs.

5. That there is a large place in higher animals for the Evolution of
the Indifferent through the action of use and habit.

6. That the position for Initiative in Evolution here advanced is no
bar to unlimited research.

INDEX.

Adami, Professor. “Medical Contributions to the Study of Evolution,”
21.

Ancestry, primate, 235, 236.

Anthropology, 4.

Ape: Arrangement of hair on forearm of, 43.

----Papillary ridges on hand and foot of, 164.

----Bursæ of, 184–186.

----Muscles of, 213, 214.

Artists, Evidence from, 66.

Ass: Hair-patterns of, 82.

Baboon, Chacma, papillary ridges on hand and foot of, 165, 166.

Bartholinus, Erasmus, 126.

Bateson, Professor, 9, 20, 22, 33, 149, 255.

----“Materials for the Study of Variation,” 9–13, 22, 210.

Bayliss, Professor, 244.

Bear, Parti-coloured (_Æluropus melanoleucus_): Hair-patterns of,
121, 122.

Beddard, Mr., 118.

----“Animal Colouration,” 206.

Bell, Sir Charles, 205.

Bergson, 205.

Bongo (_Tragelaphus euryceros_): Hair-patterns of, 118.

Bonney, Professor. “The Story of Our Planet,” 3.

Bower, Professor, 21.

Brooks, Professor, W. K., 20, 202.

Bursæ, description of, 179, 180.

----Human, enumerated, 180–183.

----Experiments as to, 186–190.

Canidæ: Hair-patterns of, 98–102.

Capybara, epidermis of, 151.

Chimpanzee, papillary ridges on hand and foot of, 164, 167, 168, 176.

----Bursæ of, 184, 185.

Clark, Sir Andrew, 30.

Cold and warmth sensations of human skin, 220–230.

Coote, Captain, 194.

Correlation, 28.

Correns, 11.

Cow, hair and habits of, 87–91.

----Fly-shaker muscles of, 90, 211, 212.

Crime, detection of a, 5.

Cunningham, J. T., 21.

Darwin, 1, 2, 15, 35, 39, 40, 139, 145, 147, 239.

----“Origin of Species,” 2, 8.

----“Descent of Man,” 2.

----Three Blows to, 9.

----On human eyebrows, 64, 65.

Darwin, Sir Francis, 20, 21.

----On Mnemonic theory of Heredity, 20.

Darwinism, 9, 15, 25, 145.

Dendy, Professor. “Outlines of Evolutionary Biology,” 21.

de Vries, 11, 24, 27, 145, 190.

Dog: Arrangement of hair of, 27, 28, 34, 100–102.

----Habits of, 98, 99.

Dyer, Professor Thiselton, 210.

Earth Wolf, epidermis of, 150.

Echidna, epidermis of, 151.

Elliott, Professor Scott, 98, 126.

----“Prehistoric Man and his Story,” 43, 47, 226.

Environments, Discontinuous, 31–33.

Epidermis: Varieties of, found in mammals, 145.

----Stimuli and response, 145–153.

Eyebrows, hairs of human, 64–73.

----Interpreted by wrinkles, 67.

Facilitation, 240, 246–248.

Felidæ: Hair-patterns of, 92–97.

----Snout of, 94.

Flexures of hand and foot, description of, 170–172.

----Chief types of, 172.

----Meaning of, 173–177.

Foot of Man, 155, 156.

----Papillary ridges on, 159, 160.

----Flexures of, 176, 177.

Foot of Man, Plantar arch of, 192–194.

----Muscles of, 214–217.

Forearm, arrangement of hair on, 41.

Galton, 157; On chiromantic creases, 170.

Galvani, 126.

Geikie, Sir Archibald, 3.

Genealogy, 4.

Germinal Selection, 19, 20.

Gibbon, flexures of foot of, 176.

----Bursæ of, 185.

Gibbon, Hainan, papillary ridges on hand and foot of, 164, 165.

Giraffe: Habits of, 115.

----Hair-patterns of, 117.

Gorilla, papillary ridges on hand and foot of, 164.

Haeckel: Pithecoid Ancestors of Man, 1.

Hair-direction, causation of, 140–144.

----Summary of conclusions with regard to, 141.

----Phenomena of, 37, 38.

----Experimental Inquiry into, 125, 126.

----Steps of Inquiry into, 40, 124, 125.

Hair-pattern, Dynamics of, 44, 45, 46, 50.

Hand of Man, 155, 156.

----Papillary ridges on, 157–159.

----Flexures of, 176, 177.

----Muscles of, 214–217.

Harris, Dr. H. Wilder, 147, 154.

Harris, Mrs. Wilder. _See_ Whipple, Miss Inez.

Hartmann, 213.

Hedgehog, epidermis of, 152.

----Papillary ridges on hand and foot of, 162, 163, 166.

----Flexures on hand and foot of, 173.

Hepburn, Dr., 148, 159, 162.

Heredity, Mnemonic theory of, 20.

Herschel, Sir John, 126.

Hill, Professor Leonard, 224.

Historian a biologist, 2.

Horse: Arrangement of hair on side of neck of, 51–63.

----Habits of, 75.

----Hair-patterns of, 75–82.

----Compared with Zebra, 83–85.

----Effect of harness upon hair of, 126–136.

----Fly-shaker muscles of, 211.

Howes, G. B., 12.

Hutchinson, Professor Jonathan, 188.

Hutton, 3.

Huxley, 5, 8, 126, 192, 200, 217.

Insectivores, 237, 238.

Jackson, Hughlings, 241.

Jevons, 124, 125, 126, 140.

Johnston, Sir H. H., 96, 201.

Jones, Professor Wood, 230.

----“Arboreal Man,” 195, 245, 248.

Kammerer, 21.

Keith, Professor, 112, 188, 189, 190, 195, 196, 208, 215, 216, 217.

----On functions of platysma, 113.

Kerr, Professor Graham, 224.

----On Embryology, 246, 247.

Kiang (Thibetan Wild Ass): Hair-patterns of, 119.

Kinkajou, epidermis of, 153.

Kropotkin, Prince, 21.

Lamarck, 13, 21, 22, 33, 35, 145, 147, 247, 255.

Lamarckian hypothesis of organic evolution, 19, 20, 22, 24, 25, 26,
28, 30, 31, 138, 205.

Lankester, Sir E. Ray, 20, 23, 45, 141, 190, 204.

Lemur: Arrangement of hair on forearm of, 43.

----Hair-pattern of, 46.

----Papillary ridges on foot of, 161, 162, 164, 165.

----Black-headed, epidermis of, 153.

----Ring-tailed, epidermis of, 153.

----Flexures of foot of, 176.

Lion: Hair-patterns of, 92–97, 207.

Livingstone, 92.

Llama: Hair-patterns of, 119, 120.

Loris, Slow: epidermis of, 154, 155.

----Papillary ridges on foot of, 161, 166.

Lydekker, 86, 92, 94, 115, 118, 119, 168, 195.

Lyell, 3, 178, 192.

----“Principles of Geology,” 3, 46.

Macacus, flexures of hand and foot of, 176.

Macalister, 215, 217.

McBride, Professor, 21.

Macdonald, Professor, 190, 244, 245, 247.

McDougall, Professor: On Physiological Psychology, 24, 25, 225, 253.

MacEwen, Sir W., 188.

McTaggart, Dr., 142.

Malthus, 2, 15.

Malus, 126.

Mammals, palms and soles of, 150–153.

Man: hair and habits of, 103.

----Arrangement of hair on back of, 104.

----Passive habits of, 106, 107.

----Arrangement of hair on chest of, 108, 109.

----Palm and sole of, 155, 156.

----Papillary ridges on hand of, 157–159.

----Papillary ridges on foot of, 159, 160.

----Flexures of palm and sole of, 176, 177.

----Plantar arch of, 192–194.

----Muscles of hand and foot of, 214–217.

----Changes in habits of, 234, 235.

Marmoset, Papillary ridges on foot of, 161.

Mendel, 11, 15, 26, 145, 190.

Mercier, Dr.: On Causation, 141, 142.

Mill, John Stuart, 141, 142.

Mole, epidermis of, 150.

Monkey, papillary ridges on hand and foot of, 164.

Mule: Hair-patterns of, 82.

Murphy, Dr. John B., 189.

Muscles: Anatomists’ views of, 201, 202.

----Initiative in, 202, 203.

----New, 205.

----Unstriped, 205, 206.

----Facial, of expression, 207–209.

----Fly-shaker, 210–212.

----Skeletal, 212, 213.

----Skeletal, of Primates, 213, 214.

Neural phenomena, 239.

Nervous System: Some aspects of the, 223–225.

----Place of the, in Evolution, 238, 239.

----Raw materials of the, 240, 241.

----Integration of raw materials of the, 241, 242.

Oken, 126.

Ollier, 188.

Onager, Hair-patterns of, 82.

Opossum, American, epidermis of, 151.

----Azara’s, epidermis of, 153.

Orang, papillary ridges on hand and foot of, 164.

----Bursæ of, 185.

Organic Evolution, consideration of problems of, 24–28.

----Factors in, 27.

----Cross-roads in, 203–205.

Owen, Richard, 10.

Oxen: Hair-patterns of, 87–91.

Palm, skin of, 147–156.

----of Man, 155–156.

Papillary ridges, some undersigned experiments in, 166–169.

Paterson, Dr. C., 188.

Pearson, Professor Karl, 34, 141, 142.

Phalanger, epidermis of, 152.

Pitt, Miss Frances, 94, 95, 251.

Plantar arch, of man, 192–194.

----How it was built, 194, 195.

----Equipment of, 196, 197.

----Description of, 197–199.

Plasto-diēthēsis, 34, 145, 195.

Platysma, Struggles of the, 111–114.

Playfair, 3.

Pocock, Roger, 75.

Poincaré, Henri, 157.

----Principles of method, 36.

Porcupine, Canadian Tree, epidermis of, 151, 153.

Poulton, Professor: “Essays on Evolution,” 86.

Prescott’s “Conquest of Peru,” 120.

Pressure, Examples of the effects of, upon hair-direction, 127–136.

Primates, epidermis of, 153.

Rabbit, epidermis of, 151.

Records, Interpretation of, 110.

Reflex arches, formation of, 231.

----Some historical illustrations of, 231–234.

----Of Insects, 236, 237.

----Of Mollusca, 236, 237.

----Of Birds, 236, 237.

----Evidence of production of new, 242–246.

Reflexes: Stimuli of, 249–256.

----Scratch, of the dog, 249.

----Purposes of, 250–253.

----Scratch, of the cat, 253.

Rivers, Sources of, 4.

Romanes: 19, 39, 40, 145.

----On Weismann, 17, 18.

Roux, 19, 145.

Russell, The Hon. Bertrand, 142.

Russell, E. S. On Lamarck’s theory, 20.

Saint-Hilaire, Geoffrey, 10.

Sapajou, Brown, papillary ridges on hand and foot of, 165.

Schafer’s “Text Book of Physiology,” 219, 220, 226.

Scratch reflex; of the dog, 249.

----Of the cat, 253.

Selous, 92, 115, 118.

Sherrington, Professor, 218, 226, 229, 238, 244, 245, 249, 250, 251,
253, 254.

Skin, Human: Distribution of Touch Corpuscles, 219.

----Distribution of Touch Spots, 219.

----Distribution of Cold and Warmth Sensations, 220.

----Distribution of Cold and Warmth Spots, 220, 221.

----Stimuli of pressure, 222, 226–230.

----Stimuli of cold, 226–230.

----Stimuli of pain, 226–230.

----Stimuli of warmth, 226–230.

Sloth, Two-toed (_Cholæpus didactylus_): Hair-patterns of, 122, 123.

Smith, Dr. E. Barclay, 201, 216.

Sole, skin of, 147–156.

----Of Man, 155, 156.

Spencer, Herbert, 28, 177.

Squirrel, epidermis of, 152.

----Papillary ridges on hand and foot of, 162, 166.

----Flexures of hand and foot of, 175.

Squirrel-monkey, papillary ridges on foot of, 161.

----Flexures of foot of, 176.

Starling, Professor, 227, 244.

----On Facilitation, 240, 246.

Still-born children, subcutaneous bursæ of two, 183, 184.

Stimuli, 30, 31.

----Of touch, 219, 226–230.

----Of cold, 220, 226–230.

----Of warmth, 220, 226–230.

----Of pressure, 222, 226–230.

Stout, Professor, 252.

Summary of conclusions arrived at, 257, 258.

Thomson, Professor J. Arthur, 20, 22, 23, 24, 25, 28, 29, 34.

----On Heredity, 22.

Touch Corpuscles, 219, 227, 228.

Touch spots, 219, 225, 227, 228.

Tschermak, 11.

Ungulates, even-toed, 86–91.

----odd-toed, 74–85.

Vernon, Dr.: “Variations in Animals and Plants,” 28.

Vulpine phalanger, flexures of foot of, 173, 175.

Wallace, Professor, 2, 39, 40, 46, 145.

Weber’s Law, 222.

Weismann, 9, 11, 14, 16, 17, 18, 21, 22, 24, 25, 26, 86, 139, 177,
210, 245, 255.

----Twelve points, 15, 16.

Weismannism, 17, 18, 19, 26, 145.

Welton, Mr., 142.

Whipple, Miss Inez (Mrs. Wilder Harris), 154, 162.

----Criticism of “The Direction of Hair in Animals and Man,” 137–139.

Wolff, 189: “Law of Bone Transformation,” 205.

Young, Arthur, 143.

Zebra: Comparisons between horse and, 83, 84.