Consideration of Weismann's Arguments 183 



service to the animals in a protective way also, but never- 

 theless the productive cause would remain always a 

 functional adaptation. 



From the preceding instances in which the action of 

 the color of the environment upon the external surface 

 of the animal appears to be direct we pass on to those 

 in which this action is indirect. Thus many fishes, 

 amphibians, reptiles and cephalopods are capable of 

 changing their color in a very short time and thus of 

 putting themselves always in accord with the very vari- 

 able color of the environment. The color of the environ- 

 ment which determines that of the animal does not act 

 nevertheless, in this case, directly upon the elements of 

 the skin, the chromoblasts, which produce the color; but 

 by a complicated nervous apparatus connecting these 

 elements with the part which is first stimulated by the 

 color. This part is sometimes constituted merely by 

 the nerve ends of the skin, at other times by the retinal 

 nerve ends of the eye. In the latter case if the optic 

 lobes of the brain are artificially destroyed the capacity 

 of changing color disappears. 144 



Further, according to LeDantec, many colorations of 

 the skin that are now fixed and correspond to the hence- 

 forth unchanging color of the environment are derived 

 from former colors that changed voluntarily with the 

 different colors of the environment, of which one certain 

 color has remained, persisting to the exclusion of all the 

 others. 145 



One could perhaps also adopt the opposite view. Just 



144 Weismann : The Effect of external Influences upon Develop- 

 ment. P. 26 27. 



145 Le Dantec : Lamarckiens et Darwiniens. Paris, Alcan, 1904, 

 Chap. XIV : Le mimetisme lamarckien. P. 129 149. 



