

THE EVENTS OF THE HUMAN CARDIAC CYCLE 75 



normal subject, over long periods, and more especially in associa- 

 tion with pregnancy, hard toil, or advancing years, brings them 

 into a domain, closely approaching, if not included within that of 

 physiology. 



Marey and his associates ; Chauveau (* 7 ) and Fran9ois-Franck( n ), 

 were amongst the chief pioneers of graphic records. The collected 

 observations of Marey, published in his books of 1863 ( 33 ) and 1881 (** b ), 

 are comprehensive. In La circulation du sang, &c., are found 

 records of almost all visible pulsations of the normal human body. 

 Numbers of tracings taken from the healthy or diseased, experimental 

 observations, and records of apparatus combine to form a rich store- 

 house of facts, never equalled before or since, for the study of 

 huemodynamic problems. The apparatus figured, and employed in 

 the experiments, show an almost unrivalled wealth of ingenuity, and 

 many of the instruments in their original or slightly modified forms 

 are still in general use. 



The methods of sphygmography are too well known to need de- 

 scription. Sphygmographs fitted with additional levers are numerous, 

 and serve in the procuration of simultaneous tracings from apex beat, 

 arteries, jugular vein, liver, fontanelle, or chest wall. The mechanism 

 used in clinical work upon the jugular pulse, the apparatus with which 

 we are chiefly concerned, is described later. The best receiver for 

 cardiographic records is perhaps Marey's, consisting essentially of a 

 cup, covered by a rubber membrane to which a button is attached. 

 But a hollow uncovered receiver answers well for general purposes, 

 and may be employed over a less restricted field. 



In animals the earliest work on intra-auricular and intra-ventricular 

 pressures was carried out by Marey's school. Small rubber balloons 

 tied over the extremities of narrow metal sounds were passed through 

 jugular vein or aorta into the corresponding chambers of the heart, 

 and records of the pressures within these cavities were obtained by 

 connecting the metal tubing to tambours supplied with levers and 

 writing styles. It might be supposed that the introduction of such 

 sounds into the auricle or ventricles would seriously interfere with 

 their normal functions. This, however, is not the case. Chauveau 

 relates that he passed a double cannula of the sort, fitted with 

 balloons for auricle and ventricle, into the right heart of a horse, 

 without disturbing the pulse rate, or the meal of which the animal 

 was at the time partaking (Assoc. franc, p. lavanc. d. Sciences, 1887). 



The apparatus used by the earlier workers for the actual records 



