IV 



ELECTROMOTIVE ACTION IN MUSCLE 



405 



diphasic variation, during spontaneous activity of the mammalian 

 heart, when led off from two points of the 

 ventricle (base and apex). But while in 

 this case the base is at first ahcai/x negative 

 in the frog's heart, corresponding with the 

 invariable direction of the excitatory, or 

 contraction, wave from base to apex in 

 the mammalian heart (although this is 

 generally the case, as appears from the 

 recent experiments of Bayliss and Starling, 

 40) there are obvious exceptions, in which, 

 by reversal, either the apex becomes nega- 

 tive earlier than the base (which Waller, 

 I.e., holds to be normal), or there is 

 only a monophasic variation. In this 

 last case there has usually been some _ 

 injury to one of the points led off, by 

 lesion, etc. Bayliss and Starling (I.e.} 

 find that it is possible by unequal warm- 

 ing, or cooling, of the ventricle in the 

 spontaneously beating dog's heart, to reverse ^ 

 the direction of the two phasic action 

 currents. It is even sufficient to warm 

 or cool the inspired air. 



By means of the capillary electrometer j 

 it is possible to show the phasic action 

 current of the heart in the uninjured body 

 of an animal, or man, either by pushing Flo . iss.- 

 two fine needle electrodes through the 

 breast- wall into the ventricle, and con- 

 necting these with the electrometer, or by 

 leading off from different points of the 

 body-surface (41). In this case a lead-off 

 from the mouth is equivalent to leading 

 off from the base of the ventricle a 

 lead-off from the rectum, or from a pos- 

 terior extremity, to leading off from the 

 apex. In addition, the following combina- 

 tions were found (on man) to be favourable for leading-off (cf. 

 Figs. 133 and 134): 



aphic record 

 of action current in mam- 

 malian heart, investigated 

 with the capillary electro- 

 meter. 1. Spontaneous beat 

 of the heart ; the first phase 

 corresponds to negativity of 

 apex to base, the second to 

 the reverse action. 2. After 

 injury to apex of ventricle. 

 3. After injury to ibase of 

 ventricle. 4. Excitation 

 effects with artificial excita- 

 tion of apex. 5. Excitation 

 effects with artificial excita- 

 tion of base. (A. D. Waller.) 



