Control of Fibrillation in the Mammalian Heart. 



309 



on the surface become more vigorous and clearly much coarser, the dissociation 

 becoming much less fine and larger groups of fasciculi contracting together ; 

 there is evidently an extension of conduction through inter-fascicular junctions 

 that were formerly blocked. On palpation the muscular substance feels of 

 good tone, and the gradation from fineness to coarseness of fibrillation is very 

 clearly realised — the sensation of universal turmoil due to the fine rapid 

 dissociated twitchings throughout the ventricular walls grading into more 

 vigorous contraction waves of coarser type, and these again into beats giving 

 the normal feeling of uniform, hardening of the muscle (figs. 7 and 8), 



A. 



B. 



Fig. 7. — Spontaneous recovery from fibrillation in 30 seconds, preceded, by coarsening of 

 the fibrillar movement. Urethane, 2'5 grm., had been given hypodermicallj', in 

 addition to chloroform. In A, the fibrillation was caused by shocks sent into the 

 ventricle at the rate of 480 per minute. A brief tachycardia precedes the fibrilla- 

 tion. - In B, recovery is seen, preceded by slower and coarser oscillations. 



