308 Mr. J, A. MacWilliam. The Mechanism and 



normal. The pseudo-fibrillation at once ceases when the stimulated area is 

 disconnected from the rest of the muscle, e.g., by forcible clamping, etc., or 



Fio. 5. — Rabbit's heart (R.V.). Faradisation with 800 units induced first a rapid 

 tachycardia, then pseudo-fibrillation which promptly stops at the end of the 

 faradisation. A blood-pressure record taken at the same time showed a great fall, 

 with minute oscillations showing on the tracing. 



Pig. 6. — Pseudo-fibrillation induced almost immediately in fully developed form by 

 faradisation ; it ends with a larger oscillation when the stimulation ceases. 



when it is cut off — as may be done in the perfused heart — or when it is 

 rapidly cooled. In pseudo-fibrillation there has not been established in the 

 mass of the muscle outside the stimulated region a mechanism which ensures 

 the continuance of the movement after the impulses emanating from the 

 excited area have ceased or have been excluded — in striking contrast to what 

 holds good in the case of true fibrillation. This method of differentiating 

 between pseudo-fibrillation and fibrillation may be more easily applied in the 

 case of the auricles, by isolation of the appendix after the stimulation has 

 been applied to the tip. 



Mode of Recovery from Fibrillation. 

 When the ventricles are recovering from the state of typical fibrillation, 

 with the aid of massage and of drugs, as stated later, the oscillations visible 



