IV 



ELECTROMOTIVE ACTION IN MUSCLE 



403 



photogram that the first " phasic action current " follows the 

 excitation at a short interval, the apex being for an infinitesimal 

 period, and very rapidly, positive to the base of the ventricle, 

 after which there is a longer interval, in which the electrometer 

 shows no deflection ; then follows immediately the somewhat 

 longer second (positive) phase of the action current, when the 

 apex is negative to the base. On injuring the ventricle at one 



Fn.. 130. a, Photographic record of action current in the Frog's heart, with artificial excitation (as 

 in Fig. 12", a). The interruptions of the dark line mark the moments of excitation, h, Photo- 

 graphic record of action current after injuring the apex of the ventricle. The variation 

 becomes monophasic. (Burden-Sanderson and Page.) 



of the two leading-off contacts, one phase of course disappears, 

 and the variation becomes purely negative, i.e. monophasic (Fig. 

 1-"0, Z>). Similar tracings of the spontaneously beating heart 

 have been photographed by other investigators, e.g. Fig. 131, 

 A. I). Waller, which at first sight differs from the results of 

 Sanderson and Page, but coincides essentially with them. Here 

 we have a simultaneous record of the contraction curve (It, //), 

 and the effect (c, c) produced on the capillary electrometer by the 



