THE SHARK'S TEETH 



ceases to produce something new. Then, from all 

 these novelties, life makes a choice, and makes the 

 best possible use of them for its diverse functions. 



Snapping up a victim in deep water is a simple 

 operation. The shark, dashing along, has only to bear 

 down, opening its mouth wide, and it can swallow 

 everything at one gulp. The teeth act as hooks to 

 prevent the prey from slipping away: only in certain 

 instances do they act as cutters. Their function is 

 comparatively simple. If that was all they were for, 

 their shape would take one form only, in due relation 

 to their purpose. But this is not the case, since, despite 

 the unity of function, we find an astounding diversity 

 in the way the teeth are shaped and fitted in the 

 various genera and families of sharks. In them we 

 find a complementary principle of diversification 

 which, having no connection with the function itself, 

 is bound up with the nature of the creature, and 

 depends upon it alone. Even if we agree that the 

 function can create the organ, we are forced to admit 

 that it does not govern considerations either of form 

 or state. 



Natural History, without degrading itself in any way, 

 can content itself with describing what it finds out, 

 and going no further. But the human mind, even the 

 most realistic and concrete of human minds, always 

 desires to go beyond present facts and find out what 

 lies beyond them. In the labyrinth of things dis- 

 cernible by the senses, it seeks the guiding thread 

 and, when it believes it has found it, holds on to 

 everything that appears, reasoning in accordance with 

 what it is accustomed to experience. We have needs, 

 and we make tools to satisfy them. And so we are 

 apt to think that the living Nature is in exactly 

 the same position. Nature, we say to ourselves, has 

 needs manifested by functions, and she creates tools 

 in the form of organs expressly to accomplish them. 

 When we reason in this way we forget not only our 

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