“Some of the physical phenomena of muscle fatigue,” with demonstration of tracings

The investigation of the subject has been continued by the employment of a method by which the isotonic curves of all the contractions of an excised non-curarized muscle stimulated at regular intervals, are superimposed upon a recording surface. The differences which were previously pointed out in the mode of fatigue of the muscles of the frog, the turtle and the mammal, have been confirmed. Lohmann's work, in which a frog's gastrocnemius on being heated to a mammalian temperature, shows a course of fatigue similar to that of mammalian muscle, has been repeated and found incorrect. Both that muscle and the turtle's coracoradialis profundus, similarly heated, continue to give their characteristic curves of fatigue. [See page 60 (124).]

Kaiser's method for determining the point of the isotonic curve where the contractile stress terminates, has been employed for the frog's gastrocnemius, and it has been found that as the height of the curve diminishes in the course of fatigue, the contractile stress terminates at progressively lower and lower points. The lowering of the latter does not, however, seem to keep pace with the lowering of the summit of the curve. Hence the two points seem to approach one another.