292 



Drs. W. De La Rue and H. W. Muller. [June 14, 



panied by a steady and marked decrease in the duration of the 

 latency, (b) When once maximal contractions are arrived at, con- 

 siderable increase in strength of stimulation does not alter the length 

 of the latency. (c) After a certain point has been reached, further 

 increase in strength of stimulus (hyper-maximal) causes elongation of 

 the latent period associated with signs of injury to the tissue. 



5. Fatigue must attain a considerable degree before it materially 

 affects the length of the latency. When it once begins to produce 

 an effect it rapidly lengthens the latent period of muscles removed 

 from the animal or in which circulation has ceased. 



6. Changes in temperature, even minimal in amount, cause a 

 marked alteration in the latency. 



Lowering of temperature is accompanied by a steady elongation, 

 and elevation by a rapid shortening of the latent period. When the 

 heat becomes intense (for frog over circa 36° C.) the length of the 

 latency seems again to increase, as the muscle passes into heat rigor. 



7. In observing the above variations in the duration of the latency, 

 we have failed to find the wide extremes given by some authors as the 

 limits of this phase of the contraction of striated muscle 



V. " Experimental Researches on the Electric Discharge with 

 the Chloride of Silver Battery. Part IV." By WARREN 

 De La Rue, M.A., D.C.L., F.R.S., and Hugo W. Muller, 

 Ph.D., F.R.S. Received June 11, 1883. 



(Abstract.) 



The authors recall that at the conclusion of the third part of their 

 researches,* they stated that they intended to make an investigation 

 on the dark discharge, and the special conditions of the negative dis- 

 charge ; this paper contains a number of experiments, more especially 

 on the latter subject, and also others intended to throw light on the 

 general nature of the electric discharge through gases. 



The first part of the paper describes some experiments made with 

 vessels of different forms in order to ascertain whether the dimensions 



* " Phil. Trans." vol. 171, p. 65. 



