Wound Reparation—A ctinian Tentacles an7 
possessed of a certain definite internal physiological condition, and 
under a certain definite set of external conditions, namely, the sum 
of all those physico-chemical factors which immediately affect it, 
is at any given instant capable of two or more different modes of 
behavior? ‘This, I believe, is the critical question for our decision 
between “machine-theory” and “‘vitalism.” Whatever we may 
think regarding the possibility of a final solution of the question 
it is only in the continued search for structure within structure, 
mechanism within mechanism, that we can now see any avenue 
of approach toward a close-range view of the two alternatives. 
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