LETTERS 



CAN THE MALE INFLUENCE THE COLORATION OF EGGS ? 

 To the Editors of British Birds. 



Sirs, — In noting {supra, p. 83) the occurrence of the interbreeding of" 

 Song-Thrush and Blackbird, it is stated that " Mr, Adam,son considers 

 that the male influences the colour of the egg-shell in such a case, but 

 this seems impossible of belief." 



On page 199 of Newton's Dictionary of Birds, 1893-96, it is stated : 

 " A most important, but still unexplained, allegation is that eggs, 

 containing hybrids, are not exactly Hke the eggs of the race or species 

 of the female, but more or less resemble also the eggs of the race to 

 which the fertilizing male belongs. Instances of such mongrel eggs 

 are mentioned by Nathusius [Zeitschrift f. Wissensch. Zoologie, XVIII., 

 page 299) ; and other well- authenticated instances would fori^n valuable 

 contributions to any of our scientific periodicals." 



In 1903 I was given an egg laid by a Canary hen (pure) when mated 

 with a Goldfinch cock. This egg, which I still have, is more like that 

 of a Goldfinch than that of a Canary. At the same time in my aviary 

 here, I was mating Silver-Pheasant hens with Common Pheasant cocks,, 

 and the eggs laid by this cross were certainly somewhat darker in colour 

 than those laid by pure Silver-Pheasants. 



I regret that I cannot bring forward further evidence to corroborate 

 Mr. Adamson's opinion, but I think that a discussion on the question 

 in the pages of your magazine would be most interesting. 



Hugh S. Gladstone.. 



[That a male bird can influence the colour of the shell of the egg laid 

 by the female to which it happens to be mated, seems to us a physiological 

 impossibility. The well-known variabiHty in the coloration of eggs- 

 makes it easy to understand how such a belief could have arisen. It 

 seems to us that the cases cited by Mr. Gladstone can only be considered 

 as ' ' allegations " (to use Dr. Gadow's word in the passage from Newton's 

 Dictionary) since he brings no evidence to show that the eggs he speaks 

 of diflEered from those laid by these individual birds when mated to 

 birds of their own species. — Eds.] 



A CURIOUS UPSTROKE IN FLIGHT. 



To the Editors of British Birds. 



Sirs, — The accompanying photograph of a Pigeon may possibly be 



of interest to your readers. The wing is, apparently, being raised, 



for it is flexed at the wrist, whereas in the downstroke it is straightened 



at the wrist and elbow. But though the upstroke is in progress, the- 



