286 



SCIENCE. 



[Vol. XVI. No. 407 



of some of his shorter works has appeared ; and, now that we have 

 a good sketch of his life, English readers can easily learn all they 

 may wish to know of the great pessimist of Germany. 



The Colours of Animals, their meaning and Use. especially con- 

 sidered in the Case of Insects. By Edward Bagnall Poul- 

 TON. (Tiiternational Scientific Series, Vcl. LXVII.) New 

 York. Appleton. 13". 



With this volume another new and valuable member is added 

 to the classical International Scientific Series. It comes to us 

 v.ith the fascinating qualities which accurate and well-written 

 accounts of animal life must have both for the general reader and 

 the biologist. Mr. Poulton has given his book a general title, 

 though it treats mainly of tlie origin of colors in insects and more 

 especially in moths and butterflies. This use of a general title 

 may be excused on the ground that nearly all the difficulties in 

 explaining the evolution of color in the animal world are met with 

 among insects. After devoting an introductory chapter to the 

 structures in animal tissues whereby color's are produced, ttio 

 author proceeds to discu-s the origin of colors by means of natural 

 selection. Animal colors are classified as non-significant and sig- 

 nificant; and the latter category is again stibdivided into colors of 

 direct physiological value to the organism (chlorophyl, pigment, 

 etc.), colors of protective and aggressive resemblance, colors of 

 protective and agressive mimicry, warning colors, and colors dis- 

 played in courtship. Each of these classes of significant colors is 

 then tal'en up in order, and discussed at length, with numerous 

 illustrations drawn mainly from the group of lepidopterous in- 

 sects. It is impossible in this brief notice to do full justice to the 

 wealth of interesting examples with which the author presents us. 

 Only a very small portion of the work deals with the hackneyed 

 cases of mimicry and protective resemblance found in zoological 

 text-books. Many of the observations are original, and others 

 are taken from the recent works of reliable investigators. Per- 

 haps the most original portion of the volume is that which treats 

 of the author's own experiments on the chrysalides of the butter- 

 flies. He exposed larvae to surfaces of difi'erent colors during pu- 

 pation, with results which may be briefly summarized in his own 

 words : — 



"I worked upon the allied small tortoise- shell butterfly {Vanessa 

 uriicce). which can be obtained in immense numbers. In the ex- 

 periments conducted in I8S6, over 700 chrysalides of this species 

 wei'e obtained, and their colors recorded. Green smToundings 

 were first employed in the hope that a green form of pupa, un- 

 known in the natural state, might be obtained. The results were, 

 however, highly irregular, and there seemed to be no suscepti- 

 bility to the color. The pupae were, however, somewhat darker 

 than usual, and this result suggested a trial of black surroundings, 

 from which the strongest effects were at once witnessed. The 

 pupsB were, as a rule, extremely dark, with only the smallest 

 trace, and often no trace at all, of the golden spots which are so 

 conspicuous in the lighter forms. These results suggested the use 

 of white surroundings, which appeared likely to produce the most 

 opposite effects. The colors of nearly 150 chrysalides obtained 

 under such conditions were very surprising. Not only was the 

 black coloriug-matter as a rule absent, so that the pupse were 

 light-colored, but there was often an immense development of the 

 golden spots, so that in many cases the whole surface of the pupae 

 glittered with an apparent metallic lustre. So remarkable was the 

 appearance, that a physicist to whom I showed the chrysalides 

 suggested that I had played him a trick, and had covered them 

 with gold-leaf. These remarkable results led to the use of a gilt 

 background as even more likely to produce and intensify the glit- 

 tering appearance. . . . The results quite justified the reasoning; 

 for a much higher percentage of gilded chrysalides, and still more 

 remarkable individual instances, were obtained among the pupae 

 which were treated in this way." 



Warning colors are discussed at some length, and many inter- 

 esting examples and experimental results adduced. There is a 

 decided antithesis between warning and protective colors; as 

 " the object of the latter is to conceal the possessor from its ene- 

 mies, the object of the former is to render it as conspicuous as 

 possible." It is shown that warning colors are usually accompa- 



nied by a nauseating taste, strongly smelling or irritant fluids, etc. 

 Attention is called to the fact that there is a general similarity in 

 the warning colors of all animals, the prevalent patterns being 

 alternating bands of striking colors, and that consequently ene- 

 mies soon learn not to attack conspicuous and unusually colored 

 animals, because a few experiments have taught them to associate 

 these striking patterns with disagreeable tastes and odors. 



In the chapter on mimicry, more examples, we think, might 

 have been introduced. Many startling cases of Hymenoptera 

 mimicked by Diptera seem to have escaped the author's notice. 

 The clai-sical case of South American heliconids and pierids, long 

 since described by Bates, really merits fuller treatment than it has 

 received on pp. 232, 233. 



The work closes with several very interesting chapters on the 

 colors used in couriship. This is perhaps the most interesting 

 Ijortion of the work, as it deals very successfully with a subject 

 about which there is still wide difference of opinion among zoolo- 

 gists. Poulton takes his stand with Darwin, and maintains that 

 the peculiar colors, appendages, etc., displayed during courtship 

 by one of the sexes (usually the male) in the presence of the other, 

 owe their origin to sexual selection. This differs from the stand- 

 point taken by Wallace, who denies that the so-called secondary 

 sexual characters thus originate. He maintains that they receive 

 their explanation in natural selection pure and simple. It would 

 be difficult, we believe, to explain many of the facts cited by 

 Poulton, notably Peckham's observations on the courtship of spi- 

 ders, from Wallace's standpoint. 



At the end of the book is given a table illustrating the author's 

 classification of animal colors. Although the Greek derivatives 

 to designate the different uses of colors are well chosen, they will 

 probably not he generally adopted. Zoologists will probably con- 

 tinue to speak of mimetic rather than pseudaposematic and pseu- 

 depisematic colors. 



The text is provided %vith sixty six woodcuts and a chromolith- 

 ographic frontispiece illustrating a remarkable case of mimicry in 

 South African butterflies. 



NOTES AND NEWS. 



The College of Physicians of Philadelphia announces that the 

 next award of the Alvai'enga prize, being the income for one year 

 of the bequest of the late Senor Alvarenga, and amounting to 

 about a hundred and eighty dollars, will be made on July 14, 1891. 

 Essays intended for competition may be upon any subject in medi- 

 cine, and must be received by the secretary of the college on or 

 before May 1, 1891. 



— A lady, writing to the British Medical Journal, says she re- 

 cently heard a young girl of fourteen years " whistle," as her 

 people called it; but •' %varble " it really was. for she kept her 

 mouth slightly open, and the lips merely trembled, the notes being 

 formed in the throat, the centre of it working as a bird's does 

 when singing, and the sounds produced were exactly like those of 

 blackbirds and thrushes. She warbled several airs to pianoforte 

 accompaniments faultlessly, and most beautifully modulated; and 

 so powerful were the notes, that her grandmother, who was ex- 

 cessively deaf, could catch every one, without the slightest effort, in 

 another room a little distance off. In the same room some notes 

 were deafening when she poured them out at the forte parts. 

 She had been self-taught entirely from " whistling" to her dog 

 and sitting in the window to " vvarble" to the birds. 



— The flora of the Kutais and Tchernomorsk regions, on the 

 eastern coast of the Black Sea, says M. Kuznetsoff in the "Iz- 

 vestia" of the Eussian Geographical Society {Nature, Nov. 6), 

 belongs, as already known, to the Mediterranean region of ever- 

 green trees. Next comes the region of West European flora, 

 characterized by the extension of the beech-tree, and offering on 

 the slopes of the mountains the very same subdivisions as one is 

 accustomed to see in the Alps That region extends over the 

 provinces of Kuban and Terek as far east as the water-parting 

 between the Terek and Sulak Rivers. The territory to the east of 

 it was formerly thought to have a flora more akin to that of Asia, 

 but a distinctly European flora appears again on the eastern slopes 



