46 



EXPERIMENTAL I'll YSIOLOG Y 



The mean rate of work is given in grm 

 mm. per second in the last column. 



From the tracing and from the 

 measurements given in the table the fol- 

 lowing points can be induced. 



1. As the temperature rises the latent 

 period, as measured by this method, gra- 

 dually decreases, at first with some 

 rapidity and then more slowly. These 

 experiments, however, do not prove that 

 the true latent period is diminished, for, 

 as above explained, there are several 

 factors at play tending to make the 

 measurement by this method too high. 

 The differences can probably be entirely 

 accounted for in this experiment by the 

 increase in the rate of propagation of the 

 muscle wave as the temperature rises. 



2. The period of contraction becomes 

 markedly shorter as the temperature rises : 

 at first the rate very rapidly increases, 

 but after about 15° C, though still in- 

 creasing, its rate of increase is much 

 slower. 



3. The period of relaxation varies in 

 the same manner, but to a more marked 

 degree. When the temperature is low 

 relaxation is slower than contraction, in 

 many experiments very much more so 

 than in this particular instance. At higher 

 temperatures relaxation is carried out 

 more rapidly than contraction. 



4. Perhaps the most interesting point 

 in the whole series is with regard to the 

 height of the twitch. In this case the 

 maximum height was at 7° C, and the 

 height diminished as the temperature rose 

 to 20° C, at which a relative minimum 

 height occurred. When the temperature 

 was still further raised the height of twitch 

 began once more to increase, and tended 

 towards a second maximum at about 

 30° C. 



