SPECIES IDENTITY OF NUCLEUS-PLASMA NORM 493 



cally and ontogenetically, there is a unity in that the mechanism, 

 the mode of reaction of nerve "cells, is fundamentally identical 

 in all animals whatever their differentiation, as declared by the 

 constant trend of the nucleus-plasma curve. Thus the curve 

 from the crayfish duplicates exactly the trend of the curve from 

 the Purkinje cell of man; for every shift in the relation in man, 

 there is a corresponding shift in the crayfish, though somewhat 

 modified. On the side of the stimulus, there is a closer unity 

 in that all adequate stimuli call forth an identical anatomical 

 response. Complementing the whole, this identity within a 

 species of the mass relation of nucleus to plasma comes to unify 

 and standardize even to a numerical constancy the reaction of 

 each type of cell. 



A new basis of comparison of the variability between individuals 

 results. Variability comes consequently within narrower limits 

 and is made to rest on fewer factors than is the usual conception. 

 Thus Adaini says on the first page of his ''Principles of pathology:" 

 "No two living beings, although belonging to the same species 

 and the same family, are structurally identical, nor even born 

 identical; and if this be true of structure it is true also of the out- 

 come of structure — namely, function. There is thus no absolute 

 standard of either structure or function in any one species." 

 While undoubtedly this is true to a degree which will be clear and 

 of more particular application in the point discussed by him, 

 namely, the difficulty of demarcation between the normal and 

 abnormal, yet it would appear that there is a fixed underlying 

 identity. It is not an identity of entities but of relations of 

 entities. If the unifonnity of a given stimulus in kind, duration, 

 and intensity be granted and if the two biological factors of de- 

 viation, namely, senility and depression, be excluded, the factors 

 of variability in functioning power and capacity of the nerve 

 cell are reduced to two, first, the absolute differences in size of 

 cells among different individuals, and, second, the most certain 

 differences in the quality of the protoplasm. That the difference 

 in quality of the protoplasm is amply sufficient to explain indi- 

 vidual variations when the complicating factors above are ex- 

 cluded the experimental evidence leaves little doubt. The 



