SPECIES IDENTITY OF NUCLEUS-PLASMA NORM 489 



by a smaller figure for the resting cell and subsequent events, 

 that is, the amount of activity belonging to a degree of depression, 

 are commensurately based on that lower figure, not on the original 

 norm. In other words, I should be willing to predict that measur- 

 ing cells of the same grade of depression as it attacks all stages 

 of activity, the changed ratio resulting from that depression would 

 fall below or rise above the changed level of the likewise depressed 

 resting cell for the whole series in proportion to the changed rest- 

 ing cell level, though in the same sequence as for normal activity. 

 This could only happen for a fixed quantitative reaction dimin- 

 ished by a fixed amount of interchange of material. It is a 

 concrete thing that instead of the plasma's being eleven times 

 larger than the nucleus as in the first stage of normal activity, 

 it is only nine times larger in a certain degree of depression for 

 that stage and that these figures belong respectively and identi- 

 cally to the normal resting cell and the corresponding depressed 

 resting cell. This is no more remarkable than the demonstrated 

 fact that as the Purkinje cell progresses from its embryonic 

 state to its nucleus-plasma norm, from a small coefficient figure 

 to a higher one with the growth of the plasma, the changes of 

 activity for any point in that progress are quantitatively based 

 on the figure which subtends the resting cell belonging to that 

 point. Thus, in a ten-day puppy, at which age all phases of 

 activity are definitely recognizable, the nucleus-plasma norm 

 is about four. The changes of activity are definitely based on 

 that figure, rising above or falling below it as happens for the 

 adult for eleven. The undeveloped cell duplicates the mecha- 

 nism, in Donaldson's apt words ('13) it is a "working model," 

 but the quantitative interchange is less. 



Returning to the question mentioned earlier as to whether the 

 nucleolar substance is actually increased in depression, the 

 measurements give now undoubted evidence that it is. It could 

 not be a chromatin increase which is the main factor, because 

 from the natm'e of the process new formation of chromatin is 

 failing and the continuance of the failing resorption for a time 

 prevents the accumulation in great excess within the nucleus of 

 what may still be formed. Objectively, the excess of intranuclear 



