470 



Drs. G. F. Yeo and T. Cash. 



muscle fibres might be avoided. The temperature of the room was 

 from 17° to 18°'5 C. 



In the case of fatiguing by simple induction shocks, 100 stimula- 

 tions were delivered (one every 2") from Ludwig's clock between the 

 registration of every two stimulations. The results showed that 

 whether in the case of the curarised muscle or of the healthy muscle 

 stimulated indirectly, the first 5 — 700 shocks produced but very 

 slight changes, not amounting frequently in all to an increase of over 



of a double vibration, or •00055". 



A curious result occurring occasionally after a few hundred stimu- 

 lations only had been administered was that the latency became 

 actually diminished to a slight extent, namely -00027" to "00044", as 

 if the moderate amount of exertion through which the muscle had 

 passed favoured the more rapid consummation of the changes in the 

 muscle preliminary to contraction. This diminution was followed by 

 a return through the original to a more rapidly increasing latency. 

 The prolongation after 900 — 1,000 contractions is distinct -00132" 

 to *00222", whilst after 1,300 — 1,500 a rapid prolongation associated 

 with loss of excitability (as shown by the long shallow curve with 

 greatly retarded relaxation) is seen. 



The following figures illustrate the course of such a case. Gastroc- 

 nemius, 100 contractions produced after each curve by maximal 

 stimulations given every 2 seconds. About 1' rest between each set 

 of stimulations. 



Latency in fraction of D.V.= t !~q". 



Normal latency =2 '2 



100 stimulations =2 2 



200 „ =2-15 



300 „ =2-15 



400 „ =2-18 



500 „ =2-2 



700 „ =2-2 



1,000 „ =2-45 



1,300 „ =3-15 



When tetanus was used as a means of fatigue the interrupted current 

 was admitted for 10" to the muscle, and after the fibres had relaxed 

 so that the lever had regained the original abscissa the comparison 

 curve was taken. 



We find that the change occurring in the latency is not altogether 

 dissimilar to that of the muscle stimulated by simple induction shocks, 

 that is to say, that the increase during the first 6 — 8, 10" stimula- 

 tions is not very great ; but that after this point the latency tends to 

 increase rapidly till at the 13th, 15th, 10-second tetanus a much pro- 



