402 THE ZOOLOGIST. 
only birds which have been observed to turn black from feeding 
on hemp-seed, nor is hemp-seed the only seed which conduces to 
such a change of colour. Larks have been known to become 
black after being fed for some time on hemp-seed; and the late 
Mr. Blyth informed us that he had seen one of the little 
Amandavat Finches which had become black, though fed entirely 
on canary-seed.”* Again, there is the ‘‘ change produced in so 
many of the Green Parrots by the native peoples of Guiana, who, 
by feeding these birds on a special diet, consisting largely of 
pounded corr or maize, produce eventually yellow-coloured 
birds.” + A pair of American Screech Owls (Megascops asio) 
which were fed in captivity largely on liver, and which were 
originally in typical grey plumage, exhibited subsequently, especi- 
ally in the larger female Owl, an actual change from grey to red- 
brown in individual feathers, and the red phase was not thought 
entirely, if at all, due to new feather-growth.{ By mixing madder 
with the food of a female mammal, Flourens produced a red 
colour in the bones of the fetus. By placing the eggs of a 
Salmon Trout in waters which only nourished White Trout, Coste 
noticed the eggs became gradually paler, and produced Trout 
which had lost the characteristic colour of their race.§ “Ifa 
Horse has an addition of arsenic to its usual food, its hair be- 
comes more glossy ; and Holmegreen has proved that if Pigeons 
are fed with meat they change not only the colours of their 
feathers, but also their odour.’’|| In the Salmonoids the flesh is 
frequently of a marked pinkish hue, “brought about by the 
crustaceans on which these carnivorous fishes so largely feed.” 4 
By changing or varying the food of lepidopterous larve, much 
variation has been produced in the depth of colour of the 
imagines.** 
The whole problem of the colouration of mankind centres 
largely on the question of what was the tint or hue of the skin of 
* ‘Nat. Hist. Selborne,’ Harting’s edition, p. 118, note. 
+ J. J. Quelch, Papers, ‘‘World’s Congress on Ornithology,” p. 124. 
{ A. P. Chadbourne, ‘The Auk,’ new series, vol. xiii. p. 321. 
* § De Quatrefages, ‘The Human Species,’ p. 247. 
|| ‘ Problems of Nature, Researches and Discoveries of Gustav Jaeger,’ 
Engl. transl. p. 38. 
qj Lydekker, ‘ Roy. Nat. Hist.,’ vol. v. p. 494. 
** Of, Kock, Goss, Gregson, and others, 
