484 DAVID H. DOLLEY 



thought of their making an appreciable difference, since their 

 cell bodies corresponded with the most normal cells (see same 

 animal in table 1). That the higher coefficient figure for this 

 first series was due to senility is proved by the results after 

 selecting cells unaffected by senility (table 1) and corroborated 

 by the second series from Experiment 31 in table 5 of frankly 

 shrunken senile cells. The series from Experiment Cerebellar 

 Section 4 represents also cells with only shrunken nuclei. 



It must be specified that the senility here discussed is a natural 

 senility (Dolley '11 a) the final fatigue of Hodge ('94) the in- 

 crease of plasma of Minot ('90, '08). It does not refer to the 

 other possibility of permanent impairment which would eventu- 

 ally result from a depression carried beyond physiological limits 

 to actual degeneration. That this possibility of depressant 

 senility exists has been conclusively shown by R. Hertwig's 

 studies on the protozoa ('04) in which the depressant upset 

 of the nucleus-plasma relation in favor of the nucleus may be- 

 come permanent and the animals pass into degeneration and die. 

 From the severer nature of the breakdown of the plasma of the 

 depressed nerve cell, analogous changes may be predicted and 

 will be investigated. Incidentally, it seems clear enough that 

 the views of Minot and Hertwig as to the cause of senescence, 

 ''apparently diametrically opposed," as Conklin says in his dis- 

 cussion ('12 a) increase of plasma against increase of nucleus, 

 are each correct and that the difference of opinion arose because 

 there are two inherently opposite factors in senility, of which 

 each investigator considered only one. 



So far as concerns function in its inclusive sense, as a factor 

 of disturbance of the nucleus plasma relation, depression, the 

 inhibition of function, remains to be discussed. That depression 

 would change the ratio of nucleus to plasma would be predicated 

 because depression changes the structural relations of every 

 type of cell, whether in rest or in function. The resting cell is as 

 much involved in depression as is any stage of activity in which 

 depression may intervene to inhibit the further progress of that 

 activity. For the full understanding of why that is so as well 

 as to explain the quantitative nature of the changes of depression, 



