546 
David H. DoUey 
for the Piirkinje cell, in Tvliicli the uucleus-plasma relation actually sliii'ts 
to the advaiitage of the nucleus, below the normal level. While the 
access of fluid is not so denionstrated, froni the analogy with the Pur- 
kinje cell in which nuclear edema is apparent the increase of vohime 
must be mainly due to that. This stage happens, roughly speaking, 
within tiiree tinies the volunie of the resting cell. An equilibrium is then 
reached which despite the continued enlargement of both cell body and 
nucleus is weU maintained for a long period of fuither acti\'ity, though 
the advantage, slowly at first, then inore rapidly is accruing in favor 
of the cytoplasm. Finally, when as for example in one series the total 
cell vohune has reached a size ten tinies that of the resting cell, there 
is a more decided upset in favor of the cytoplasm which is due to the 
ultimate and actual loss of nuclear substance proper. This marks the 
near approach of exhaustion, though the final stage of dechromatinization 
of the nucleus, the complete exliaustion as illustrated by the Purkinje 
cell, has not beeil obtained experinientally in the primitive cells. The 
above sequence of changes is common to all types of cells. 
Accompanying these size changes, there is first an increase in cell 
substance proper. For the cytoplasm, this coiTesponds Volumetrie ally 
and to a less degree tinctoriaUy to the hyperchromatisni which is so 
pronounced in highly differentiated cells. This functional growth in 
reaction to physiological Stimulation varies in extent in different types 
of cells, but in all, sooner or later, its capacity falls, and there ensues a 
progressive loss of substance in the cell body whose niaxhnum is shown 
in edeniatous cells, devoid of chroniatic material save for a vacuolated 
peri-nuclear remnant and with only the achroniatic reticulum to denote 
its fornier existence. This qiiahtative approach to cytoplasmic exhaus- 
tion belongs to its Volumetrie exliaustion and is to be correlated with 
the Volumetrie dechiie of the nucleus. The Volumetrie decüne of the 
nucleus denotes indubitably its qualitative dechne, ei'eu withoiit its 
final dechromatinization, which as stated has not beeil observed. From 
the very dose correspondence in their preceding course, this final and 
for interpretation neghgible step is assumed to complete the parallel. 
Oll the basis of compaiison with the recuperation of the Purkinje cell 
and from the progressive upset of the nucleus-plasma relation in favor 
of the cytoplasm, the nucleus must be regarded as coniing to absolute 
inimediate exhaustion fhst with the balance of capacity on the side of 
the plasnia. Functionally, since the course of activity is measured by 
days or weeks rather than hours, the slowness of reaction and strength 
of endiirance are thereby displayed. The exhaustion discussed is not 
