188 ANIMAL PHYSIOLOGY. 
It will be borne in mind that the limbs are held together as 
by elastic bands slightly on the stretch, owing to the elasticity 
de 
Fig. 185.—Illustrations of the difference in elasticity of inanimate and living matter (after 
Yeo). 1. Shows graphically behavior of a steel spring under equal increments of weight. 
2. A similar tracing obtained from an India-rubber band. 3. The same from a frog’s 
muscle. Note that the extension decreases with equal increments of weight, and that the 
muscle fails to return to the original position (abscissa) after removal of the weight. 
of the muscles. Now, as seen in many tracings of muscular 
contraction, there is a tendency to imperfect relaxation after 
contraction—the contraction remainder or elastic after-effect, 
which can be overcome by gentle traction. In the living body, 
the weight of the limbs and the action of the stretched muscles 
on the side of the limb opposite to that on which the muscles 
in actual contraction are situated, combine to make the action 
of the muscle more perfect by overcoming this tendency to im- 
perfect relaxation, which is probably less marked, independent 
of these considerations, in the living body. This elasticity of 
living muscles, which is completely lost on death, is a fair 
measure of their state of health or organic perfection. Hence 
that hard (elastic recoil) feeling of the muscles in young and 
vigorous persons, especially athletes, in whom muscle is brought 
to the highest degree of perfection. 
This property is then essentially the outcome of vitality, 
which is in a word the foundation of the differences noted be- 
tween the elasticity of Inorganic and organic bodies. A mus- 
cle, the nutrition of which is suffering from whatever cause, 
whether deficient blood-supply, fatigue, or actual disease, is 
deficient in elasticity. We wish to emphasize these relations, 
for we consider it very important to avoid regarding vital phe- 
nomena in the light of physics merely, which the employment 
of the graphic method (and indeed all methods by which we re- 
move living things out of their normal relations) fosters. 
Electrical Phenomena of Muscle—Certain pieces of apparatus 
