SIZE CHANGES IN NERVE CELL BODIES 309 
ciding five micra section. The points one would mark for the 
diameter in either case are marked 2, and the slight deviation 
from the perfect five micra section indicated by the dotted lines 
as well as from the true median section containing AB is 
apparent. 
THE COMPARISON BY DIFFERENTIAL COUNTS 
For the technical interests of this paper only the Purkinje 
cell of the cerebellum is considered. 
First it will be of interest to discuss the results of the differ- 
ential counts which were made for the general comparison of 
exercise with the lack of it. The conditions under which both 
puppies had lived accounts to me for the striking difference that 
resulted from unaccustomed exercise. They were not merely 
rested up for a few weeks, for subsidence from activity of any 
degree goes most slowly (Dolley, lla), but they had always 
lived under general conditions unconducive to wide activity. 
TABLE 1 
Differential counts of cells 
RESTING 
han STAGES OF ACTIVITY UNCOUNTED CELLS 
© O| 2] oo] o| oD! oO] Oo] o] oO] o| ao] o Hyper- Hypo- 
a a|a\a|a|aleala|alalalal|a| chromatic | chromatic 
~ »~ a ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 
DM NIN|A|N|A|INIA|A|N|D| n\n 
Control animal..... 23 10|39|97| 6} 1) 3} 3} 3} 2} 0] 1) 0 105 7 
Exercised animal... 0 2| 7/16) 2/13} 9/21)/24)43)12] 2) O 27 _ 122 
The data from the counts are set forth in table 1. The counts 
were made from paired simultaneously cut sections from the two 
cases. In each case a start was made from a corresponding 
corner and the line of Purkinje cells followed in continuity until 
all in the section were surveyed, and then, as the full quota was 
not made up in either case, one jump was made to corresponding 
corners of a pair the third removed in the serial to avoid count- 
ing any cell twice. Kocher’s prerequisite of a complete nuclear 
membrane is as good a working basis as any, only it is to be 
remembered that if one admits hypochromatic cells whose karyo- 
some is not visible, he can only approximate the exact stage 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 27, NO. 3 
