Electromotive Phenom. of the Mammal. Heart. 273 



ni. 



The supposed tetanic character of the ventricular contraction. 



Frédéricq has come to the condusion that each ventricular con- 

 traction is composed of 3 or 4 single twitches fused together and is 

 therefore of the nature of a tetanus. He bases his conclusions on the 

 following evidence. 



1. The vibrations on the plateau of the ordinary cardiographie 

 curve, and of the tracings of intraventricular pressure, obtained by 

 Chauveau and Marey. 



2. On the descending parts of the electrometer curves (mostly 

 monophasic), obtained by liim from the heart in situ, are to be ob- 

 served small superposed vibrations, indicating the compound nature 

 of the electrical change. 



3. If the aorta be ligatured and the heart excised and the 

 electrical variation of the dying heart photographed, some of the 

 beats, just before the heart goes into delirium, show two or three 

 summits to the electrical curve. 



We have found no evidence that the cardiac contraction is te- 

 tanic; on the contrary, we have, we venture to think, established the 

 fact that each contraction of the mammalian ventricle is a single 

 wave, starting normally at the base and spreading thence over the 

 whole substance of the ventricles. 



1. With regard to Frédéricq's first argument, we have no right 

 to speak, not having made any special researches on the subject. But 

 we would suggest that the superposed curves on the systolic plateau 

 of an endocardiac pressure tracing might be equally well attributed to 

 the elastic vibrations of the ventricular and aortic walls, induced by 

 the sudden increase of pressure in their cavities, reinforced and exag- 

 gerated by the periodicity of the recording instruments employed. 



2. The small superposed vibrations on the descending parts of 

 the electrometer-curves taken from the heart beating in situ are clear- 

 ly due to vibrations of the apparatus itself, and not to any cardiac 

 event, for if we look closely at his figures, we see that they are as 



Intoniationalo Monatsschrift für Anat. u. Phys. IX. 18 



