4()0 DAVID H. DOLLEY 



reconstruction. It was predicted by Professor Hedrick from 

 the nature of the data that such would be the case. For the two- 

 niicra cells it will only be said here that Cell 8 which approxi- 

 mates the result from the wax reconstruction most closely was 

 the most suitable for application of. the prismoid formula in that 

 the polar sections of both plasma and nucleus were apparently 

 of full thickness. 



The results are regarded as so consistent, when all possible 

 factors of variation are considered, that a law is formulated as 

 follows : 



Resting undepressed nerve cells of corresponding type of all 

 individuals of a species have a mass relation of nucleus to plasma 

 which is a close numerical constant, whatever the age between 

 full development of the relation and senescence, whatever the 

 size of the anitaal, irrespective of variations in the dimensions and 

 absolute size of the cells both in the same animal and in different 

 animals, and irrespective of the degree of function in excited 

 cells of the same type in the same animal. 



Certain points in table 1 in regard to comparative sizes and 

 iielations of cells may be conveniently considered here. Only 

 the adult animals, from Experiment Muscular Exertion 32 to the 

 end, excepting Experiments Shock 36 and 37, can enter into the 

 comparison. Since the other animals were yet in progress of 

 growth, analysis is not permitted. In the first place, there is 

 no definite correspondence of size of cell to size of animal (see 

 colmnn of cell volumes). The cells of the two largest animals. 

 Experiments Normal 19 and Muscular Exertion 31, which are 

 practically of the same weight, differ widely in size. ^ While 

 Experiment Muscular Exertion 31 is two and one-half times 

 larger than Experiment Muscular Exertion 32, its cells are only 

 about 20 per cent larger. 



Levi ('05) and Conklin ('12 b) conclude that the size of the 

 nerve cell varies with the size of the animal. If there is any 

 such general rule, these data are sufl^cient to bring out a strik- 

 ing exception. But in such comparisons the effect of function 

 on the size of the cell has been disregarded (see under "Technical 

 factors"), and resting cells afford the only exact basis of com- 



