42 RESPONSE IN THE LIVING AND NON-LIVING 
will at once be seen from record D how far the fatigue 
had been removed. 
One peculiarity that will be noticed in these curves 
is that, owing to the presence of comparatively little 
residual strain, the first response of each set is rela- 
tively large. The succeeding responses are approximately 
equal where the residual strains are similar. The first 
response of A shows this because it had had long 
previous rest. The first of B shows it because we are 
there passing for the first 
time to increased stimula- 
tion. The first of c does 
not show it, because there 
(a/ 
is now a strong residual 

strain. D again shows it 
(b) because the strain has been 
removed by fifteen minutes’ 
rest. 
Fatigue under continuous 
Fic. 24.—Rarip FaricuE uNDER Con- stimulation.—The effect of 
TINUOUS STIMULATION IN(@) MuscLeE; fatioue is exhibited in 
(bo) iy Lear-sTaLK OF CELERY 5 

marked degree when a 
tissue is subjected to continuous stimulation. In cases 
where there is marked fatigue, as for instance in certain 
muscles, the top of the tetanic curve undergoes rapid 
decline. A similar effect is obtained also with plants 
(fie. 24). 
The eflect of rest in producing molecular recovery, 
and hence in the removal of fatigue, is well illustrated 
in the following set of photographic records (fig. 25). 
The first shows the curve obtained with a fresh plant. 
