﻿838 THE ENTOMOLOGIST. 



I am not able to say whether Mr. Gentry's opinion, which I 

 quoted, has any real foundation in fact or not ; but to show that 

 the idea of nutrition affecting sex is not confined to Mr. Gentry, 

 I will quote from a very interesting paper, by Mr. F. E. Beddard, 

 published in the 'Report and Proceedings of the Ealing Micro- 

 scopical and Natural History Society for 1889.' Mr. Beddard, 

 referring to birds, says (p. 55) : — 



" It appears that in many birds the males are very much more 



abundant than the females M. Stoltzmann himself reports 



203 males to 87 females among humming-birds, collected by him 

 in Peru. He attempted to explain this disproportion by the 

 apparently observed fact that the better nourished eggs become 

 females ; the worse nourished eggs, males. The female, occupied 

 with the cares of incubation, is not in a sufficiently healthy con- 

 dition to produce many well-nourished eggs. Hence the greater 

 number of births is of male birds." 



Of course there is another way of looking at it, namely, that 

 these eggs or larvse which were to produce females needed most 

 nourishment, and hence when semistarvation occurred the males 

 would be able to survive on less, and would reach the adult 

 stage, while the females would more often die. In this way the 

 same result, a preponderance of males, would be observed. 

 3, Fairfax Eoad, Bedford Park, Chiswick, W., Oct. 12, 1890. 



CONTRIBUTIONS to the CHEMISTRY of INSECT COLOURS. 

 By F. H. Perry Coste, F.C.S. 

 (Continued from p. 31^). if- 

 V. — The Chemical Aspect (continued). 



C. 



Having thus, for the present, disposed of black, perhaps it 

 would be as well to say a few words upon those eminently 

 unsatisfactory colours Brown and Grey,- although the gist of my 

 remarks thereupon is really that there is nothing to be said ! 

 So far as I can understand matters at present, these greys and 

 non-tints so common among Noctuse and Geometers, the brown* 

 shades also common in Noctuse, and even perhaps the browns of 

 manyBombyces, already enumerated, are all (physical) absorption 

 colours, just as black is ; excepting that instead of complete 

 absorption of the light rays taking place, only some or most of 

 them have been absorbed. 



Wallace apparently considers t that all these dubious browns, 



* See, however, the remarks on pp. 221 and 223. 



t 'Tropical Nature,' p. 188. I ought to add, however, that in this passage 

 Wallace is referring to animal colours generally, and not to insects specially. 



