. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative. 190 COMPARATIVE PHYSIOLOGY. return to its original length; and if a series of weights which differ by a common increment be applied in succession and the degrees of extensions compared, as may be done by the graphic method, it will be ap- parent that the increase in the extension does not exactly correspond with incre- ment in the weight, but is proportionally less. With an inorganic body, as a watch- spring, this is not the case. Further, the recoil of the musc
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative. 190 COMPARATIVE PHYSIOLOGY. return to its original length; and if a series of weights which differ by a common increment be applied in succession and the degrees of extensions compared, as may be done by the graphic method, it will be ap- parent that the increase in the extension does not exactly correspond with incre- ment in the weight, but is proportionally less. With an inorganic body, as a watch- spring, this is not the case. Further, the recoil of the muscle ailev the removal of the weight is not perfect for all weights; but within certain narrow limits this is the case, i. e., the elasticity of muscle, though slight (for it is easily over-extended), is perfect. When once a muscle is over-extended, so weighted that it can not reach its original length almost at once, it is very slow to recover, which explains the well-known duration of the effects of sprains, no doubt owing to some profound molecular change associated with the stretching. The tracings below show at a glance the difference between the elasticity of muscle and of ordinary bodies. It is a curious fact that a muscle during the act of contraction is more extensible than when passive ; a disadvantage from a purely physical point of view, but prob- ably a real advantage as tending to obviate sprain by preventing too sudden an appli- cation of the extending force. It will be borne in mind that the limbs S™rod"'attach!? to are held together as by elastic bands slight- wiTaiens""^"'"^'™'* 1^ «" t^^e stretqh, owing to the elasticity of the muscles. Now, as seen in many tracings of muscxilar contraction, there is a tendency to imper- fect relaxation after contraction—the contraction remainder or elastic after-effect, which can be overcome by gentle trac- tion. In the living body, the weight of the limbs and the action of the stretched mu
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