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.’** 
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.**° 
One could perhaps also adopt the opposite view. Just 
“4Weismann: The Effect of external Influences upon Develop- 
ment. P. 26—27. ; : 
457 @ Dantec: Lamarckiens et Darwiniens. Paris, Alcan, 1904, 
Chap. XIV: Le mimétisme lamarckien. P. t29—149. 
