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truth of them is not essential to the argument, but since the 



frog in the lump of chalk or coal furnishes an excellent 



illustration, we will for the moment assume them to be true. 



At any rate, even if no frog has actually inhabited a cavity 



in chalk or coal, it is tolerably certain that a tadpole so 



placed would develop into a perfect animal ; for if we capture 



a tadpole, and, supplying it with proper food, rear it in a 



vessel in our own houses, it also develops into a frog perfect 



in body and mind. In all respects the animal is as active 



and his faculties are as keen as those of a frog born in the 



marshes. If released he is ready to take his place with, and 



battle for existence against his fellows of the pond. Like 



the dragon-fly, he knows his proper food and how to seek it ; 



he knows his enemies and how to avoid them ; he will search 



for his mate and will know her when they meet. Neither 



the aquarium nor the narrow walls of chalk or coal cramp 



body and mind such as they are. His physical and mental 



development depends solely, or almost solely, on the amount 



of food he is able to secure. But he is practically incapable 



of learning. People who have kept frogs know them as the 



stupidest of pets. If now and then a frog learns or appears 



to learn, the amount of his acquired knowledge is certainly 



infinitesimal. 1 



391. But suppose we took a baby at birth and, were it 

 possible, confined it in a narrow chamber so contrived that 

 growth but not movement was permitted, and in which 

 neither light nor sound nor other messages from the outer 

 world reached it. Suppose by some means we kept it alive, 

 cramped and in the still darkness, for twenty or thirty years, 

 and then opened the chamber. We should find a creature 

 scarcely human. Certainly all that distinguishes man from 

 the brutes would be absent. The creature would have the 

 hair and teeth and some other structures of the adult man. 

 The rest of its body would be little bigger than an infant ; 

 for, as is well known, the trunk, limbs, and brain of man, 

 though not his hair nor teeth, develop mainly as a result of 

 use and exercise. 2 Thus a limb, completely paralyzed during 

 infancy, grows little if at all. Possibly the bones of the 

 imprisoned baby would grow somewhat ; but the voluntary 

 muscles, except the breathing muscles, would disappear. 



1 The most learned frog of which. I have knowledge is one mentioned 

 by the late Professor George Romanes (Animal Intelligence, p. 255). It 

 is possible his correspondent was not a very accurate observer. Never- 

 theless frogs are so nigh in the scale of life that it is tolerably certain 

 that they are able to learn a little, if a very little. 



2 See 438, footnote. 



