280 



DEFINITE ACTION OF THE 



Chap. XXIII. 



Erman 39 states that this occurs with the Kirgisian sheep when brought to 

 Orenburgh. 



It is well known that hemp-seed causes bullfinches and certain other birds 

 to become black. Mr. "Wallace has communicated to me some much more 

 remarkable facts of the same nature. The natives of the Amazonian 

 region feed the common green parrot (Chrysotis /estiva, Linn.) with the fat 

 of large Siluroid fishes, and the birds thus treated become beautifully 

 variegated with red and yellow feathers. In the Malayan archipelago 

 the natives of Gilolo alter in an analogous manner the colours of another 

 parrot, namely, the Lorius garrulus, Linn., and thus produce the Lori 



These parrots in the Malay Islands and South 

 America, when fed by the natives on natural vegetable food, such as rice 

 and plantains, retain their proper colours. Mr. Wallace has, also, re- 



Kin 



corded 40 a still more singular fact. 



(of 



CC 



C( 



iC 



<c 



<c 



a curious art by which they change the colours of the feathers of many 

 birds. They pluck out those from the part they wish to paint, and 

 inoculate the fresh wound with the milky secretion from the skin of a 



small toad. 



The feathers grow of a brilliant yellow colour, and on bein^ 



plucked out, it is said, grow again of the same colour without any fresh 

 " operation." 



Bechstein 41 does not entertain any doubt that seclusion from light 

 affects, at least temporarily, the colours of cage-birds. 



It is well known that the shells of land-mollusca are affected by the 

 abundance of lime in different districts. Isidore Geoffroy St. Hilaire 42 

 gives the case of Helix lactea, which has recently been carried from Spain to 

 the South of France and to the Eio Plata, and in both these countries now 

 presents a distinct appearance, but whether this has resulted from food or 

 climate is not known. With respect to the common oyster, Mr. F. Buck- 

 land informs me that he can generally distinguish the shells from different 

 districts ; young oysters brought from Wales and laid down in beds where 

 "natives" are indigenous, in the short space of two months begin to 

 assume the "native" character. M. Costa 43 has recorded a much more 

 remarkable case of the same nature, namely, that young shells taken 

 from the shores of England and placed in the Mediterranean, at once 

 altered their manner of growth and formed prominent diverging rays, like 

 those on the shells of the proper Mediterranean oyster. The same indi- 

 vidual shell, showing both forms of growth, was exhibited before a society 

 in Paris. Lastly, it is well known that caterpillars fed on different food 

 sometimes either themselves acquire a different colour or produce moths 

 different in colour 44 



39 ' Travels in Siberia/ Eng, translat., 



vol. i. p. 228. 



Wallac 



< 



Travels on the 



Amazon and Eio Negro/ p. 291. 



41 ' Naturgeschichte der Stubenvogel ' 

 1840, s. 262, 308. 



, 42 ' Hist. Nat. Gen./ torn. iii. p. 402. 

 4S ' Bull, de la Soc. Imp. d'Acclimat./ 



torn. viii. p. 351. 



44 See an account of Mr. Gregson's 

 experiments on the Abraxus grossu- 

 lariata, ' Proc. Entomolog. Soc./ Jan. 

 6th, 1862 : these experiments have 

 been confirmed by Mr. Greening, in 

 'Proc. of the Northern Entomolog. 

 Soc./ July 28th, 1862. For the effects 





