484 DAVID H. DOLLEY 



two, for again the nerve cell specialized toward irritability has 

 two processes of reaction, activity and depression. 



The attempt here will be to cover a few essential points of 

 what in scope belongs to a monograph. Much that has ap- 

 peared discordant in observation and d-eduction is now clearly 

 harmonized in respect to the nerve cell. 



There is first the view of Minot ('90, '95, '08) as opposed to 

 the view of R. Hertwig ('03, '08), apparently diametrically op- 

 posed, as Conklin ('12, '13) remarks. On the one side, there 

 is the natural senility, the 'final fatigue,' so correctly recognized 

 by Hodge, the (relative) increase of plasma of Minot, structurally 

 the eventually absolute upset of the nucleus-plasma relation in 

 favor of the plasma, and metabolically the senility of final or- 

 ganic exhaustion. On the other side, there is the 'physiological 

 degeneration' of Hertwig as a senescent state, the permanent up- 

 set of the nucleus-plasma relation in favor of the nucleus, and 

 metabolically the blocking and hence progressively lowered level 

 of reciprocal interchange between plasma and nucleus. Thus in 

 the cell specialized for function, increase of plasma and increase 

 of nucleus each has its disproportionate display relative to the 

 other, and the views of Minot and Hertwig both apply in respect 

 to the phase which each encountered and investigated. Conklin, 

 however, is entirely correct that changes in the nucleus-plasma 

 relation are not the cause of senescence : they are indexes of the 

 two possibilities of lowered metabolism which will be considered. 

 Instead of the cause, such changes in size relations are an effect. 



In discussion of the metabolic relations of the two distinct 

 kinds of senility, it will first be shown that they accord with the 

 generalization of Conklin and Child in respect to senility as a 

 general state. Conklin says, ''Longevity is determined by the 

 duration of the excess of an anabolism over katabolism" ('13, p. 

 191); "Slow interchange (between the chromatin and the pro- 

 toplasm) is the condition of slow metabolism, and of senescence" 

 ('12, p. 62). Child ('11) concludes that senescence and rejuvenes- 

 cence are caused by a decrease or an increase in the fundamental 

 metabolic reactions. A decrease in the power of constructive 

 metabolism, as Conklin terms it, is obviously the metabolic 



