228 The Effect of Fatigue on Muscle Nuclei 
all cases control animals were selected from the same lot of tadpoles, 
attention being paid to the size and similar conditions. 
Fatigued and control tadpoles were dropped into the same dish of kil- 
ling fluid, carried through all subsequent steps together, imbedded par- 
allel to one another, and cut with the same stroke of the section knife. 
It would seem from this that the differences between the fatigued and 
the control cells must be due to the fatiguing process. 
Hxperiment 1.—Tadpoles stimulated for 72 hours in the water wheel 
apparatus and then teased with a needle until motionless. Killed with 
warmed corrosive-acetic fixative. 
Haperiment 2.—Tadpoles stimulated 3 hours by rapidly moving wheel 
and teased until motionless. The time required to tease this set of 
animals to a motionless condition was much less than the time required 
for set number one. Killed in picro-acetic fixative. 
Experiment 3.—Tadpoles stimulated for 24 hours and teased as above. 
Time required to tease to motionless con- 
dition longer than for set two. Killed in 
picro-acetic fluid. 
an 
gfe) 
ee / 
Se eee os is =e y 
ee cone GH 
HG. ale 
= Fic. 1. Resting muscle cells. Tail of tadpole. qi oil immers. Carm. Zeiss. 
N. = Nucleus. 
Fic. 2. Fatigued muscle cells. Tail of tadpole. 1 oil immers. Carm. Zeiss. 
N. = Nucleus. 
In staining the tissue a variety of dyes were used, methylene blue 
and eosin giving the best results. the blue forming a definite contrast to 
the red. 
Tn the sections of fatigued muscle the nuclei appear shrunken and 
crenated to a greater or less degree, where the normal nucleus (Fig. 1) 
shows a regular outline and is better defined. The fatigued nuclei (Fig. 
2) appear more lightly staining and less granular than the control. 
Further the sections of fatigued muscle take the blue stain more lightly 
as regards the whole section than does the resting muscle. 
