ELECTRO-CARDIOGRAM 



809 



of the base of the heart to the apex, and two negativity of the apex to 

 the base. The capillary electrometer has now been superseded by the 

 string galvanometer (p. 700) for the investigation of the human electro- 

 cardiogram (Figs. 302-305). But a sample of the records obtained by 

 the former method (Fig. 299), with the corresponding constructed 



Fig. 302. Human Electro-Cardiogram 

 (String Galvanometer) (Einthoven). 

 Led off from the two hands, i mm. 

 of the abscissa corresponds to o-oi 

 second. 



Fig. 303. Human Electro-Cardio- 

 gram (String Galvanometer) 

 (Einthoven). Led off from right 

 hand and left foot. 



0,1 Sec. 



Fig. 304. Schematic Representation of Electro-Cardiogram (String Galvanometer) 

 (Einthoven). Five points are lettered at which the curve changes sign. P cor- 

 responds to the auricular contraction; the other four are included in the ven- 

 tricular cycle. 



Fig. 305. Electro-Cardiogram from Man (String Galvanometer) (Lewis). From a 

 case of paroxysmal tachycardia. The heart-rate was 200 a minute. The upper 

 notched line is the time-trace in one-fifth seconds. 



electro-cardiograms, (Fig. 300) is reproduced for their historical interest. 

 In their main features it is obvious that they agree with the records 

 obtained by the string galvanometer. The electro-cardiograms are 

 distinctly affected by exercise and by the position of the body, and very 

 markedly in disease. The galvanometer may be connected with the two 



