THE RECOVERY FROM DEPRESSION 483 



passes out its nuclear materials and they are consumed. There 

 is no block of reciprocal relations between plasma and nucleus, 

 with its possibilities from unused stuff in physiological depression, 

 even without chemical influence directly transforming the chro- 

 matin in experimental and toxic depression. 



In conclusion, metabolic pigment is definitely derived from 

 nuclear material in all somatic cells which have been studied 

 from this point of view. With this widespread evidence for a 

 specific origin which applies to one type of nerve cell, it must 

 apply to all nerve cells. This disposes of the histogenesis for 

 both the normal and abnormal. Abnormal autochthonous pig- 

 mentation in all nerve cells reacting like the Purkinje cell must 

 come by way of depression. Activity in such cells is excluded, 

 the only other possibility. For the normal pigmentation, in all 

 other cell types for which it is likely that the further differentiation 

 of the chromidial apparatus which all nerve cells possess takes 

 the direction of pigment formation, whether a specific and fixed 

 characteristic or possibly a functional by-product, the effect of 

 abnormal conditions remains also to be determined. Cytologi- 

 cally, this covers the possibilities. If the generalization goes too 

 far in its inclusiveness, at least the apology is that it is a 

 prediction which enables one intelligently to investigate and 

 experiment. 



For the elucidation of abnormal states, while the pigmentation 

 of depression is a degeneration in the Purkinje cell in the sense 

 of a perversion of its normal activities, it results by a process, 

 and one which finds its homologue in normal situations. 



THE DUALITY OF THE SENESCENT PROCESS IN THE NERVE CELL 

 (SENILITY OF FUNCTION AND SENILITY OF DEPRESSION) 



Previous work (Hodge, '94, Dolley, '11, '14, Kurtz, '15) on 

 the nerve cell has shown that the inevitable result of its natural 

 functional metabolic activities is old age. The present work 

 determines a senility of contrasted sort in structure and in 

 genesis and the dual nature of senility for a highly differentiated 

 cell is thus established. There were two possibilities and only 



