482 DAVID H. DOLLEY 



matin is the representative type ; there has been a deeper reaching 

 loss of the substances which provide for recuperation, a loss ab- 

 solutely demonstrated by the final disappearance of the nucleus 

 and later of the plasma. If plasma and nucleus disappeared 

 together, the equilibrium might be expected to have been main- 

 tained, that is, there should be no change in the nucleus-plasma 

 relation. On the contrary, the nucleus suffers throughout dis- 

 proportionately. The inevitable trend, as between the relative 

 size of nucleus and of plasma, is toward a progressively and 

 relatively larger plasma. The present results, so far as the senile 

 resting cell is concerned, bear this out. The figures for the 

 nucleus-plasma coefficients are uniformly higher than any ob- 

 tained for cells in their prime, that is, their nuclei are relatively 

 smaller (table 5, Senility). Furthermore, as the senile cells 

 measured are limited to those showing shrinkage alone of the 

 nucleus or of the body and nucleus and as the selection stopped 

 at those with so much organic deficiency as loss of the karyosome, 

 the figures prove that this final upset in the relation expresses 

 itself fairly early in the development of senility. This is an 

 important point in the estimation of senile capacity and may 

 indeed be taken as evidence, with the principle established, that 

 the qualitative deterioration of the senile cell has begun. On 

 the other hand, these figures do not differ greatly in size from 

 the usual constant. That is, the changed basis of reciprocal 

 relations, of mutual interchange of materials, is not a marked 

 one, and the cell has not departed greatly from the original 

 basis of equilibrium. Though likely the numerical ratio increases 

 to a steadily increasing degree throughout the senile necro- 

 biosis there is no evidence that the cytoplasm is preserved at the 

 expense of or independent of the nucleus but the invariable pic- 

 ture is that of association of plasmatic decline with nuclear decline, 

 a certain balance is preserved, and so function must continue in 

 the usual quantitative way until the nucleus goes, though on a 

 progressively lower level of capacity. 



In explanation of the figures in table 5, it may be said that the 

 first series of Experiment 31 was the first series measured from 

 this animal. Some cells with senile nuclei were included without 



