324 Dr. F. Gotch. Records of Electrical Changes [Mar. 5, 



discovery that the electrometer, when appropriately connected with the 

 surface of the body, shows the electromotive changes which accompany each 

 beat of the heart in situ. These have been supplemented by observations 

 upon the exposed beating heart (Bayliss, Starling, etc.). The latest records 

 of this type in the case of man are those which Einthoven has obtained by 

 the use of his delicate string galvanometer. All these records differ 

 fundamentally from the records obtained by Burdon-Sanderson with the 

 excised heart of both the frog and the tortoise, for, although the effects are 

 diphasic, the second phase in the mammalian heart is of the same sign as the 

 first (as in fig: 2), instead of beiug of opposite sign. It has thus been 

 suggested that there is a want of parallelism between the activities of the 

 mammalian heart and those of the heart in the frog and the tortoise. 



The present experiments show that the changes observed when the frog's 

 heart remains in situ and supplied by blood are precisely similar to those 

 known to occur in the mammalian heart, they also bring out a further new 

 point of no little interest, since, under certain conditions, a return wave of 

 activity proceeding from the apex to the base is clearly demonstrable ; this 

 wave succeeds that which proceeds from the base to the apex. It is this 

 return wave which is largely responsible for the extensive terminal phase of 

 the whole electromotive effect in the beating heart. 



The observations now carried out have been made under a considerable 

 variety of conditions, only a few of which can be at present referred to. The 

 recording instrument employed was the extremely sensitive electrometer 

 used by myself for the investigation of nerve. In order to indicate its 

 sensitiveness, I may state that with one contact on a locally injured surface 

 the full change under the other uninjured contact caused a very extensive 

 displacement of the mercury meniscus which, when magnified by the lens 

 used for its projection upon the recording photographic plate, displayed itself 

 as a movement of from 150 to 180 mm. 



The heart of the pithed frog was carefully exposed and left covered by 

 pericardium ; two contacts were then placed, one across the auriculo- 

 ventricular groove, the other upon the ventricle apex. Each natural beat 

 of the heart, thus left in situ, was associated with electromotive changes 

 which caused electrometer movements of the character shown in fig. 2. In 

 the right hand of this curve is the commencement of a heart beat, the rise of 

 the curve indicating the relative negativity of the tissue under the contact 

 upon the groove ; the point (a) is the commencement of the auricular con- 

 traction, the point (b) the commencement of the ventricular contraction //- 46 

 later. In the left part of fig. 2 the whole of the main ventricular change is 

 displayed ; it begins at the point (b) and commences to subside at the point 



