SIZE CHANGES IN NERVE CELL BODIES 307 
TECHNIC 
The unexercised animal then came into the experiment as the con- 
trol, and every precaution was taken subsequently to preserve an exact 
identity of treatment. The two were simultaneously anesthetized 
with ether through the codperation of an assistant, and killed by simul- 
taneous bleeding. Their brains were removed at the same time so far 
as possible by duplicate motions, and the specimens from each drop- 
ped at the same moment, into the same fixing fluid, in a single con- 
tainer as follows: The bottles for each individual fluid used in fixing, 
dehydrating and imbedding were divided by a perforated partition 
into two parts and the material thus separated was subjected to iden- 
tical conditions. Every transfer to the next solution was made by the 
simultaneous use of two forceps. 
The fixing agent used was 
Saturatedumencuntcrehlonidesserar sc oe eee ce eer 95 
40 per cent formaldehyde solution. ........¢...200005- 6245 03e22 520°: 5 
The material was then run through the graded alcohols,—30 per 
cent, 50 per cent, 70 per cent, 80 per cent, being iodized several days 
in the 80 per cent to remove the mercury, 95 per cent and absolute. It 
was then carried through xylol, xylol-paraffin, and two changes of 52° 
M.P. paraffin with the same precautions of identical handling. Fi- 
pay the exercised and control tissue were inbedded side by side in one 
ock. 
The sections were cut by the same stroke of the knife at five micra 
in serial, and necessarily subjected to the same conditions of staining. 
As customary, the stain used was Held’s erythrosin and toluidin blue. 
Yet, save for a certain straining at a finicky precision, the pro- 
cedure differed in no respect from previous ones, nor were the 
results in any way superior. Still Kocher is very harsh with me 
because ‘‘The control and fatigue material was handled entirely 
separately. Slight unavoidable variations in the exposure of the 
tissue to the various agents and different thickness of the cut 
sections would make such material worthless for comparative 
study.” Surely not quite so bad as that. Bichloride is bichlo- 
ride and alcohol is alcohol, and there are some of us who think 
that we get certain cell pictures because of the particular physi- 
co-chemical conditions in the cells, for we get them in the same 
animal by any fixing and staining reagent—and Kocher admits 
that he got them by his method. A microtome that can be de- 
pended upon to cut one micron serial sections, and there are 
