344 ELECTRO-PHYSIOLOGY 



appear immediately after making the artificial section. According, 

 however, to the pre-existence theory, this would still be demon- 

 strable if the injured segment were completely rigored, since 

 there would then be an unequal lead-off from the natural 

 cross-section of the next segment, as in the tendon or bones of a 

 monomerous muscle. But this is not the case ; the longitudinal 

 sectional current only lasts so long as a portion of the substance 

 of the segment provided with an artificial cross-section is living ; 

 it becomes nil when this segment is completely rigored, and only 

 recovers its former proportions when a new section is made on 

 the farther side of the tendinous intersection. 



Analogous relations exist in cardiac muscle. This stands 

 apart from other striated muscle not only in regard to the com- 

 plicated character of its fibres, which is here of no importance, 

 but also with reference to the much smaller dimensions of its 

 morphological elements, which consist of minute, microscopic cells. 

 Engelmann showed that the single cells of cardiac muscle proved 

 themselves in dying to be perfectly separate individuals, exactly 

 resembling the single constituents of polymerous muscle. The 

 process of rigor induced by section originates in the heart at 

 a very short distance from the wound, and therefore occurs more 

 quickly than in normal muscles with long fibres, so that here, as 

 in polymerous skeletal muscle, the margin between dead and 

 living muscle substance is formed in the last resort by the 

 natural surfaces, or ends, of the cells not directly injured. If, 

 notwithstanding these data, the standpoint of the pre-existence 

 theory is adopted, there is nothing for' it but to assume that 

 each single cell of cardiac muscle is furnished at its ends with a 

 parelectronomic layer, just as in polymerous muscle a parelec- 

 tronomic layer must be assumed on either side of the tendinous 

 intersection. But such a conclusion will hardly be subscribed 

 to, unless inevitable. It follows therefore from the reaction of 

 polymerous and cardiac muscle, that both the constituents of 

 the former, and the cell elements of the latter, give no external 

 electromotive response in the uninjured state. 



Analogous experiments, undertaken by Engelmann on the 

 organs composed of smooth muscle cells, yielded the same results. 

 Here too, as in the heart, the E.M.F. sinks very rapidly between 

 artificial transverse and natural longitudinal section, rising again 

 when the section is refreshed, a reaction which may also be 



