1881.] On Electrical Stimulation of the Frog's Heart, 383 



The application of this solitary wave in air to the carrying of sound. 



Errors of the phrases in general use for the explanation of the con- 

 veyance of sound. 



My theory of the mode in which sound is propagated as distin- 

 guished from the mode of its creation. 



Consideration of the aerial wave of sound, its analogy to the solitary 

 wave in water. 



The depth of the air ocean and its correspondence to that of the 

 water ocean. 



The speed of the solitary or carrier wave in each element. The speed 

 is due to the depth. What happens in the interior of the solitary 

 wave in water ? The same motions take place in the same nature of 

 aerial wave. 



Elucidation by the comparison of three equivalent oceans. 



Similarity and dissimilarity between the oscillating waves and the 

 carrier or solitary wave. 



Musical sounds in their melodic and harmonic relations to this 

 wave. Numerical nomenclature of sounds. 



How the message of the sound wave is delivered to the brain. 



VI. "On the Effect of Elertrical Stimulation of the Frog's 

 Heart, and its Modification by Cold, Heat, and the Action 

 of Drugs." By T. Lauder Brunton, M.D., F.R.S., and 

 Theodore Cash, M.D. Received May 16, 1881. 



(Abstract.) 



From the results of the recorded experiments conducted on the 

 frog's heart in its normal position and still exercising its circulatory 

 function, we have found — 



I. That electrical stimulation by a single induced shock has either 

 an obvious effect on the contraction and rhythm of the organ, or no 

 such effect is apparent. 



II. That the effect is modified by — ■ 



(a.) The time of the cardiac cycle in which stimulation falls. — Thus 

 Marey has already shown that a so-called refractory period is demon- 

 strable under certain conditions.* Well-marked variations in latency 

 when the stimulation is potent to induce a systolic contraction are to 

 be recognised. 



(b.) The strength of the stimulation applied. — Refractory periods 

 possible under minimal stimulation can no longer be demonstrated 



* The conditions of this refractory period, or " period of diminished excitability," 

 have been very fully investigated by Dr. Burdon Sanderson and Mr. Page. " Proc. 

 Koy. Soc," vol. 30, p. 373. 



