56 David H. Dolley, 



whatever the place one wishes to assign to the nucleus in the cell. 

 To deny it would be to deny that the neuron concept is only another 

 term for of mass the cellular concept. The cytoplasm and the nucleus are 

 the elements which originate the energy and transform it in the 

 nerve cell as in all cells. If it is not true here, the deepest, the 

 most far-reaching significance of the cell theory goes down. 



The only evidence, however, does nut lie in the denuding of 

 chromatin. The marked upset of the nucleus-plasma relation in favor 

 of the. plasma which brings about the dechromatinization gives proof 

 in terms of mass of the nuclear exhaustion. Though the balance of capa- 

 city remains with the cell body, its approach likewise to exhaustion is 

 shown quantitatively by its great size, its loss of substance, edema 

 and final dechromatinization. So the limit of immediate capacity is 

 reached, though, after adequate chance for recuperation, the cell 

 becomes restored to run its energy supplying course anew. The complete 

 cycle of activity is from rest to exhaustion, then from exhaustion by 

 recovery to the same starting point. While so far as one can see, 

 recovery in a young and virile animal may be complete after exhausting 

 overstrain, yet over-severe effort leads after continuance beyond a 

 certain point for each individual to premature senile, the exact 

 counter part cytologically of normal old age. Here is the principal 

 demonstration of a qualitative deterioration which sooner or later is 

 inevitable. This demonstration complements the quantitative exhaustion 

 of a single cycle of excessive work. 



The explanation why the exhaustibility or even the fatigue of 

 the nerve cell has not appeared as a factor in physiological experi- 

 mentation is not difficult to the cytologist. The reasons are many. 

 In the first place, they have dealt principally in their experiments 

 with the less differentiated types of spinal cord or ganglion. These 

 are resistant, difficult to exhaust. Such a primitive cell as found in 

 the crayfish for example (Dolley, 1914 a) requires clays, even weeks 

 of continuous stimulation in order to be driven to its limit. The lower 

 cells of vertebrates retain this more primitive characteristic in marked 

 degree, as is evident from the work of Hodge, Mann, Lugaro and the 

 early workers who dealt with such types. On the contrary, the 



