THE SPECIFIC FORM. 205 



with the work of nutrition. It is directed nutrition. 

 It consists of a simple increase from the moment the 

 element is born by the division of an anterior element, 

 and of a necessarily restricted differentiation. It is a. 

 rudimentary embryogeny. In the complex being, 

 metazoan or metaphyte, the organism is constituted, 

 starting from the Q.g^, by the growth, by the biparti- 

 tion of the elements, and their differentiation, accom- 

 plished in a certain direction and in conformity with 

 a given plan. This, again, is directed nutrition, but 

 here the embryogeny is complex. The directing plan 

 of operations is no doubt the consequence of the 

 material conditions realized each moment in the 

 organism. 



Normal Regeneration. — Not only do living beings 

 themselves construct their typical architecture, but 

 they re-establish it and continually reconstitute it, 

 according as accidents, or even ordinary circumstances, 

 tend to destroy it ; in a word, they become rejuvenes- 

 cent. This regeneration consists in the reformation 

 of the parts that are altered or carried away in the 

 normal play of life, or by the accidents which disturb 

 its course. 



Thus there is a normal physiological regeneration, 

 which is, so to speak, the prolongation of the onto- 

 genesis — z>., of the work of formation of the individual. 

 We have examples in the reconstitution of the skin 

 of mammals — in the throwing off of the epidermic 

 products constantly used up in their superficial and 

 distal parts and regenerated in their deeply-seated 

 parts ; in the loss and the renewal of teeth at the 

 first dentition and in certain fish in the fact of 

 successive dentitions ; in the periodical renewal of 

 the integument in the larvce of insects, and in the 



