CHAPTER XVI 



PROTOPLASMIC FUNCTIONS OR FUNCTIONS OF 

 COLLOID MECHANISM 



BY adopting this method of injection into the interior 

 medium we evidently limit our studies to functions exercised 

 in the interior of the tissues to protoplasmic functions. 

 It is not by shaking arms and legs that a man or an animal 

 can struggle against a poison introduced into his blood. We 

 shall have to see later whether laws discovered for proto- 

 plasmic functions apply equally to functions visible to the 

 eye, like those which demand the help of the locomotor ap- 

 paratus. We begin by the study of protoplasmic functions, 

 because it is far easier and at once gives general results. 



Whatever be the colloid substance injected, whether 

 living or not-living, when the animal resists the injection 

 without dying it seems not to have changed, that is, just so 

 long as we do not use as verifying reagent precisely that 

 colloid with which the experiment was made. Conse- 

 quently, when the use of such a reagent is neglected, we might 

 believe that the law of assimilation established in the third 

 part of our book was rigorously exact : we should even be 

 obliged to think that the animal, surviving as it does, has 

 purely and simply assimilated, transformed into its own 

 substance, the colloid which was injected into it and must 

 have served it as a food. The variations therefore, if there 

 are any, must be of little importance ; and indeed, from a 



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