SPECIES IDENTITY OF NUCLEUS-PLASMA NORM 447 



quired by disease and the technical results ran so smoothly, 

 that the following definite conclusion was stated: "For resting 

 cells of both sensory and motor types, in Cambarus virilis, there 

 is a definite relation of nuclear mass to cell mass. The coeffi- 

 cient of this relation is an identical constant among the four 

 types of primal resting cells both in the same animal and for all 

 animals of the species, whatever their size." These facts, taken 

 in connection with the constancy of the results for the Purkinje 

 cell as representing adequately the highest tj-pe of specialization 

 in animals in rest and activity toward the other extreme of the 

 scale, appeared sufficient for the further generalization that for 

 all nerve cells there is a certain definite relation of nuclear mass 

 to cell mass, which is the primal principle of Richard Hertwig's 

 nucleus-plasma relation theory ('03). 



For that phase of the relation which interests us here, namely, 

 whether the expression of this relation is an identical constant 

 for corresponding cells in all animals belonging to any parti- 

 cular species, I have felt that the induction, while reasonably 

 certain for the crayfish, was not sufficiently supported for other 

 animals, though all the facts pointed that way. It must be 

 pointed out here for the sake of a clear initial understanding 

 that this phase of species identity of the relation is not at all 

 carried by Hertwig's original statement above, nor is it necessary 

 in the application of the nucleus-plasma doctrine in the expla- 

 nation of the mechanics of function. Provided that the rest- 

 ing cell of any type of any animal have a nucleus-plasma relation 

 which is a constant for that animal, ''eine bestimmte Korrelation," 

 the shifts and final upset which occur as a result of functional 

 activity and functional depression could perfectly well be ex- 

 plained in terms of that animal's particular relation for that cell. 

 There could as well be a general correspondence in the changes of 

 function and of lack of function ontogenetically and phylogeneti- 

 cally that actually appears more constant and exact. The 

 trend could be the same without such close quantitative uni- 

 formity as that to which the mass relations invariably point. It 

 is needless to say though that the interpretation of the changes of 

 function in all its phases on this basis would not harmonize so 



