164 Animal Life and Intelligence. 



species."* Professor Mivart also reminds us that English 

 oysters transported to the Mediterranean are recorded by 

 M. Costa to have become rapidly like the true Mediterranean 

 oyster, altering their manner of growth, and forming 

 prominent diverging rays ; that setters bred at Delhi from 

 carefully paired parents had young with nostrils more 

 contracted, noses more pointed, size inferior, and limbs 

 more slender than well-bred setters ought to have ; and 

 that cats at Mombas, on the coast of Africa, have short, 

 stiff hair instead of fur, while a cat from Algoa Bay, 

 when left only eight weeks at Mombas, underwent a com- . 

 plete metamorphosis having parted with its sandy- 

 coloured fur. Very remarkable is the case of the brine- 

 shrimp Artemia, as observed and described by Schmanke- 

 witsch. One species of this crustacean, Artemia salina, 

 lives in brackish water, while A. milhausenii inhabits water 

 which is much salter. They have always been regarded 

 as distinct species, differing in the form of the tail-lobes 

 and the character of the spines they bear. And yet, by 

 gradually altering the saltness of the water, either of them 

 was transformed into the other in the course of a few 

 generations. So long as the altered conditions remained 

 the same, the change of form was maintained. 



Many naturalists believe that climate has a direct and 

 determining effect on colour, and contend or imply that it 

 is hereditary. Mr. J. A. Allen correlates a decrease in the 

 intensity of colour with a decrease in the humidity of the 

 climate. Mr. Charles Dixon, in his "Evolution without 

 Natural Selection," says, " The marsh-tit (Parus palustris) 

 and its various forms supply us with similar facts [illus- 

 trative of the effects of climate on the colours of birds], 

 In warm, pluvial regions we find the brown intensified; 

 in dry, sandy districts it is lighter; whilst in Arctic 

 regions it is of variable degrees of paleness, until, in the 

 rigorous climate of Kamschatka, it is almost white." Mr. 

 Dixon does not think that these changes are the result of 

 natural selection. " Depend upon it," he says, with some 



* St. George Mivart, " On Truth," p. 378. 



