vii MECHANICS OF THE HEART 223 



a priori, expect a certain number of tlie various characteristics found by 

 different authors in the cardiograms of healthy individuals, to be due to the 

 method or rather to the instruments employed. Hiirthle performed a double 

 series of experiments. In the first place, with the tambours of Marey, Knoll, 

 and Grunmach, lie recorded an identical impulse, mechanically produced. 

 Then with the same tambours lie successively recorded the cardiograms of one 

 healthy individual. The result of his experiments showed that while Marey's 

 tambour was not wholly free from error it recorded the impulses in such a 

 way as to reproduce their characteristics accurately. The cardiographs 

 invented by Knoll and Gnmmach, on the other hand, were very fallacious. 



The following tracing (Fig. 78), obtained by Frangois-Franck 

 from a woman suffering from ectopia cordis congenita, is convincing 

 since in this case the heart, having dropped down through an 

 abnormal opening in the diaphragm, beat beneath the skin in the 

 linea alba of the epigastrium. It is clear that the rhythmical 

 elevation determined by the ventricular systole commences exactly 

 at the close of presystole. 



FIG. 78. o.d, Cardiograms of right auricle ; r.d, cardiograms of right ventricle, recorded 

 simultaneously by two separate explorers with writing levers. (Francois- Franck.) 



No less convincing are the cardiograms obtained from man 

 under normal topographical conditions of the heart, which are 

 recorded simultaneously by an electric signal at the precise 

 moment at which the first and second sounds are first heard. We 

 have shown that the first sound is concomitant with systole, and 

 any one who questions whether it begins at the moment of 

 tension, i.e. prior to the ventricular efflux, need only study the 

 tracing obtained by Marey from the horse with a cardiographic 

 sound introduced into the right ventricle (Fig. 79). 



Starting from this well-established fact, the cardiograms of 

 the heart -beat (Fig. 80) which Edgren obtained from his 

 cardiograph, used simultaneously with the stethoscope, have 

 the same value and lead to the same conclusions as the fore- 

 going tracings of Francois- Franck. 



Since the cardiac pulse is proved to be initiated in the rapidly 

 ascending movement before the intraventricular tension has suc- 

 ceeded in opening the semilunar valves, all those hypotheses are 

 necessarily discredited which seek to explain this phenomenon. 



