SPECIES IDENTITY OF NUCLEUS-PLASMA NORM 495 



viduals with acquired absolute size and must work the same way, 

 though to what extent is yet to be defined. In fact, from another 

 point of view the inference is necessitated for a purely quanti- 

 tative reaction that the principle of increased efficiency for in- 

 creased size must hold, if a constant quality is premised. Other 

 factors being excluded, the absurdity to which this reasoning 

 would lead if there were an exact correspondence of nerve cell 

 size to body size, namely, that the larger animal is necessarily 

 the more efficient animal on the nervous side, cannot follow if 

 the present data are correct. The larger animal has the larger 

 cell only in so far as its peculiar functional demands and functional 

 usage have developed different cells. It may have nerve cells 

 smaller than the mean for its species. Further analysis is im- 

 possible until the limitations of innate growth and the relation 

 of function to growth are definitely established for the nerve cell. 

 This is as far as the facts appear legitimately to carry one. 

 To go further would be pure hypothesis. Yet with this beginning 

 of the recognition of numerically constant quantitative relations, 

 one can hardly doubt that there lie hidden relationships on the 

 phylogenetic side which perhaps will shed further light on the 

 laws governing evolution and on the side of function will lead to 

 the basis of differentiation. Can it be without significance that 

 all the cells of the crayfish are on the same nucleus-plasma level, 

 or does it mean a common degree of differentiation suitable to 

 the crayfish? If it be without significance, why should a spinal 

 ganglion cell have one relation and a Purkinje cell another and 

 so on? 



SUiM.MARY 



Numerous facts in the course of previous work pointed to the 

 induction that the individual members of a species are to a remark- 

 able degree on the same level of constancy as regards the quantita- 

 tive relation of nucleus to plasma for every type of nerve cell. 

 The evidence of the quantitative nature of the nerve cells' re- 

 action with its measured volumetric correspondence and the 

 objective recovery after functional activity to the identical prior 

 level of rest have suggested this induction most directly. Fur- 



