224 



PHYSIOLOGY 



CHAP. 



as the effect of the systolic outflow of the blood into the 

 arteries. 



Carlile (1833) and Ludwig (1848), in order to explain the 

 cardiac pulse, took into special consideration the conical form 

 assumed by the ventricular mass in systole, and the forward 



Fio. 79. Oscillations of pressure in right ventricle (V. D.) of horse, transmitted through cardiac 

 sound to recording tympanum. (Marey.) The times at which the first and second heart-sounds 

 begin to be heard are simultaneously recorded by an electric signal. 



inclination observed in the base of the ventricle, which causes the 

 apex of the heart to impinge on the wall of the thorax. But 

 since this change of form and movement of the heart is the effect 

 of systolic evacuation, it is obvious that it cannot be adduced to 

 explain the sudden rise seen in the cardiograms during the period 

 of tension, i.e. before the blood begins to stream out of the 

 ventricles. 



In a recent work Keith (1904) has taken up the idea of Ludwig, 

 developing it by subtle anatomical arguments and with ingenious 

 experimental methods for which we refer the reader to the 

 original memoir. Keith maintains that the base of the ventricle 



FIG. 80. Cardiogram transmitted to cardiograph from fifth left intercostal space in man. (Edgren.) 

 The times at which the first and second heart-sounds begin to be heard are simultaneously 

 recorded by an electric signal. 



rises slightly during presystole. This displacement depends more 

 particularly on the peculiar disposition of the pectinate muscles. 

 In consequence of this rise of the base of the ventricle, it almost 

 meets the blood which is driven towards it. When, on the 

 contrary, systole sets in, upon which the ventricle is restrained in 

 every dimension, its base is pushed out in the opposite direction. 



