11 6 Dr. J. A. Mc William. The Structure and Rhythm [Jan. 29, 



Tracing shows difference in curves of normal and artificially- excited (reversed) 

 ventricular beats. The two right-hand beats are spontaneous ones ; the two 

 left-hand beats were caused by direct stimulation of the ventricle with single 

 induction shocks. 



The muscular tissue of the isolated ventricle presents some 

 characters that are similar to those of the frog's ventricle, and some 

 that are markedly different. 



1 shall proceed to refer briefly to some points in the behaviour of 

 the eel's ventricle with regard to 



(1.) Single stimulations, electrical and mechanical. 

 (2.) Faradisation with strong and weak currents. 

 (3.) The constant current. 



With regard to the effects of single stimulations on the quiescent 

 ventricle, minimal stimulation is at the same time maximal — as in the 

 frog's ventricle. Induction shocks obtained with one Daniell's cell in 

 the primary circuit, when the secondary coil of the Da Bois Reymond's 

 induction machine completely covers the primary coil, give the same 

 strength of contraction as do shocks obtained when the secondary 

 coil is 10 cm. removed from the first-mentioned position. 



When the isolated quiescent ventricle is made to contract regularly 

 by induction shocks at certain definite intervals {e.g., 10 seconds) 

 there is, as a rule, no progressive augmentation of the contraction 

 force up to a maximum — no staircase of beats ("aufsteigende Treppe" 

 of Bowditch), like that which is so conspicuously seen in the ventricle 

 of the frog in similar circumstances. In the quiescent ventricle of the 

 eel's heart the maximum beat is almost invariably obtained at once; 



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Tracing showing beats obtained from an isolated quiescent ventricle by stimulating 

 it at intervals of 20 seconds with single induction shocks. 



the beats elicited at regular intervals by a long consecutive series of 

 shocks are almost always of exactly the same size, provided the interval 

 between the successive shocks is sufficiently long to allow full recovery 



