CHAPTER XX 



FUNCTIONAL ASSIMILATION A GENERAL BIOLOGICAL 



LAW 



LET us take a living body A, formed of parts a, 6, c, . . ., 

 each capable of multiplying on its own account, but incap- 

 able of variation in its own peculiar nature, because each 

 has arrived at the term of its differential evolution. Such 

 an example is, perhaps, to be found in certain histological 

 elements of mammals. Any definite function in the body 

 A has to define a mechanism composed of the parts a, b, c, 

 but in such way that some of the parts a, some of the parts b, 

 and some of the parts c, will be at work effectively in the 

 mechanism, each according to its own peculiar nature, 

 while, on the contrary, other parts a, b, c, will be in func- 

 tional repose. The law of functional assimilation expresses 

 the fact that the former are the seat of phenomena of assimila- 

 tion, while the latter are the seat of phenomena of proto- 

 plasmic destruction. 



If the living body A is a unicellular being, we cannot 

 recognize the parts called a, b, c, . . ., which compose it 

 and which are capable of independent multiplication and 

 destruction. Otherwise we should be able to apply to 

 such unicellular beings, decomposed into tissues, the law 

 as we have expressed it. Our ignorance of the independent 

 parts a, 6, c, . . ., obliges us to lay down the law under a 

 different form, as follows : When a sum total of circum- 

 stances B defines in the body A the function (A x B), the 



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