"^'"igos^^] Recent Literature. 91 



Part I gives a general statement of the conclusions of various authors 

 respecting the influence of climatic conditions upon the coloration of ani- 

 mals, and the results of certain experiments upon a geims of coleopterous 

 insects (Leptinotarsa) by Prof. W. L. Tower. Part II recounts certain 

 well known instances of melanism in wild birds and mammals, and other 

 dichromatic phases among birds. Part III enumerates numerous cases 

 of sporadic melanism among cage birds. Parts IV and V deal with Mr. 

 Beebe's own experiments with Wood Thrushes, White-throated Sparrows 

 and Inca Doves. 



Mr. Beebe's experiments consisted in confining a specimen of the Wood 

 Thrush, and of the White-throated Sparrow, and several specimens of 

 the Inca Dove, in a superhumid atmosphere and noting the results. The 

 food given these birds was the same as that upon which other specimens 

 of these species were fed, so that this factor is eliminated as a possible 

 cause of the changes observed in coloration. The Wood Thrush showed 

 very little change at the first moult after confinement, but markedly in- 

 creased change with the second moult, soon after which it died. With 

 the second moult the black spots tipping the feathers of the under parts 

 became much enlarged, with other minor changes in other parts of the 

 plumage. 



The White-throated Sparrow, confined under similar conditions, be- 

 came, after two moults, strongly melanistic, the change affecting nearly all 

 parts of the plumage. The Inca Doves, several of which were subjected 

 to the same conditions, and for longer periods, showed not only a general 

 darkening of the plumage but various other suggestive modifications. 

 In the case of the doves, as in the other birds, there was "a radical change 

 in the pigmentation of the plmnage .... with each succeeding annual 

 moult." In no instance, however, was there a change of color without 

 moult. 



In the case of the Inca Doves: "When the concentration of the melanin 

 has reached a certain stage, a change in color occurs, from dull dark brown 

 or black to a brilliant iridescent bronze or green. This iridescence 

 reaches its highest development on the wing coverts and inner secondaries, 

 where, in many genera of tropical and subtropical doves, iridescence 

 most often occurs." 



In discussing the significance of these changes Mr. Beebe finds reasons 

 for differing from some of the conclusions reached by Prof. C. O. Whitman 

 from the study of various species of doves and pigeons kept in confine- 

 ment for investigation, under, however, normal atmospheric conditions. 

 In respect to the Inca Doves, says Mr. Beebe: "The increase of pigment 

 in a single individual under humidity during a comparatively short period 

 of time, and the subsequent correlated development of metallic tints, 

 assume a new importance when we con.sider that, in these experiments at 

 least, mutation and natural selection have no place." 



Professor Whitman assumes that "the direction of evolution can never 



