. A text-book of physiology : for medical students and physicians . ts—flexorsand extensors—is such that the contraction of one moves thebone against the pull of the extensible and elastic antagonist. * This claim has been denied, see Ellis, American Journal of Physiology,31, 370, 1913. f Biedermann, Electro-physiology, vol. i, translated by Welby, andEngelmann, Archiv fur die gesammte Physiologie, 18, 1. t Hurthle, Archiv f. d. ges. Physiologie, 126, 1, 1909. THE PHENOMENON OF CONTRACTION. 21 It would seem that the movements of the skeleton must gainmuch in smoothness and delicacy by this arr
. A text-book of physiology : for medical students and physicians . ts—flexorsand extensors—is such that the contraction of one moves thebone against the pull of the extensible and elastic antagonist. * This claim has been denied, see Ellis, American Journal of Physiology,31, 370, 1913. f Biedermann, Electro-physiology, vol. i, translated by Welby, andEngelmann, Archiv fur die gesammte Physiologie, 18, 1. t Hurthle, Archiv f. d. ges. Physiologie, 126, 1, 1909. THE PHENOMENON OF CONTRACTION. 21 It would seem that the movements of the skeleton must gainmuch in smoothness and delicacy by this arrangement. Thephysical advantages of the extensibility and elasticity of mus-cular tissue are evident not only in the contractions of our volun-tary muscles, but, as we shall see, in a striking way also in thecirculation, in which the force of the heart beat is stored andeconomically distributed by the elastic tension of the distendedarteries. The extensibility of muscular tissue has been studiedin comparison with the extensibility of dead elastic bodies. With. Fig. 4.—a, Curve of extension of a rubber band, to show the equal extensions for equalincrements of weight. The band had an initial load of 17 gms., and this was increasedby increments of 3 gms. in each of the nine extensions, the final load being 44 gms. Theline joining the ends of the ordinates is a straight line, b, Curve of extension of a frog smuscle (gastrocnemius). The initial load and the increment of weight were the same as withthe rubber. The curve shows a decreasing extension for equal increments. The line join-ing the ends of the ordinates is curved. regard to the latter it is known that the strain that the bodyundergoes is proportional, within the limits of elasticity, to thestress put upon it. If, for instance, weights are attached to arubber band suspended at one end, the amount of extension ofthe band will be directly proportional to the weights used. Ifthe extensions are measured the relationship ma
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