On the Latent Period of Muscle Contraction. 



469 



average increase of '1625 D.V. The application of the three succeed- 

 ing 10 grm. weights would have a conjoined effect of "3384 D.V. The 

 middle weights 40 — 70 grms., as has been already noticed, have less 

 influence in prolonging the latency, their value would be about 

 •284 D.V,, whilst the last series of these has again a much larger 

 effect, equal together to '354 D.V. ; thus the extremes show greater 

 variations amongst themselves than do the constituents of the inter- 

 mediate series. 



Lever to 10 grms -1625 D.V. = -0009" 



lOgrms,, 20 „ 



20 „ „ 30 „ >.... -3384 „ = -00187" 



30 „ „ 40 „ 



40 „ „ 50 „ 



50 „ „ 60 „ V.... -284 „ =-00157" 



60 „ „ 70 „ 



70 „ „ 80 „ 



80 „ „ 90 „ J>.... •:;••■! „ =-00190" 



90 „ „ 100 „ 



Total 1-1389 



We feel inclined to hazard a corresponding division on mechanical 

 grounds as follows : — 



Lever (wt. 1 grm.) = tension of many muscle bundles very incom- 

 plete. 



10 — 40 = these bundles brought into action by the added weight. 



40 — 70 = all bundles active and unwearied. 



70 — 100 = strain of some of bundles, commencing weariness. 



During the suspension of the second 100 grms. the variation in 

 latency only amounts to about one-half of that which obtains during 

 the first 100 grms. 



Latency is then prolonged by increasing the weight, but it does not 

 increase in a definite ratio to the increase of such weight. 



5. Our attention was next turned to the effect of fatigue upon the 

 muscle in modifying the latency occurring after stimulation. To 

 induce fatigue we delivered to the muscle a certain number of opening 

 induction shocks — maximal intensity — in a given time, or we admitted 

 an interrupted current completely tetanizing the muscle for a specified 

 period. After the muscle had remained at rest for a short interval a 

 curve was taken, and the comparison of the latency of this curve with 

 that taken before the tetanus or induction shocks had been adminis- 

 tered was supposed to represent the effect of the stimulation which 

 had intervened. A weight of 10 grms. only was applied to the lever 

 during these experiments, so that injury from undue tension of the 



