in . ELECTRICAL EXCITATION OF MUSCLE 251 



currents, the contraction at the anode is not total, and under 

 certain conditions, particularly when the surface of the intestine 

 has become dry, it is evident that the immediate proximity of 

 the anode remains smooth at closure of the circuit, while in 

 consequence of the contraction of the circular muscles, innumer- 

 able wrinkles are formed on both sides of it. Nor are fche- 

 longitudinal muscle bundles of the tsenire unexcited if the anode 

 is placed anywhere along their course, only the effects are more 

 easily overlooked in this case. The immediate proximity of the 

 anode is again unexcited, while contraction occurs in the neighbour- 

 ing region. In the thin intestine, where the anatomical relations 

 are still more unfavourable to electrical excitation than in the 

 muscular integument of worms, the corresponding manifestations 

 of excitation, as described, are very difficult to analyse in detail, 

 and only the marked and extended closure contraction of the 

 circular muscles remains as a visible effect at the anode, along 

 with the local shortening of the longitudinal fibres at the kathode. 

 It cannot, however, be doubted that in the first case the longi- 

 tudinal muscles, in the second (at least with strong currents) the 

 circular muscles, also, are excited simultaneously, and to the same 

 degree (29). 



With the last-described experiments on the intestine of warm- 

 blooded animals, must naturally be classed the results of Engel- 

 mann's extensive experimental investigation on the electrical ex- 

 citation of the ureter (5). It is obvious, in view of the inferior 

 size of this tube, which consists of circular and longitudinal 

 muscles arranged similarly to the intestine, that the finer details 

 of changes of form in the two muscular layers at the poles of the 

 exciting current are here much harder to recognise than in the 

 previous cases. For this reason, an effect which only appears 

 exceptionally in the intestine, comes prominently forward in the 

 ureter, i.e. the peristaltic progress of excitation, or contraction, 

 from its starting-point. Schillbach (32) states, that on excit- 

 ing the intestine with the constant current, " a contraction 

 localised to the seat of excitation formed itself at the kathode/' 

 while at the anode a local contraction appeared, which in a few 

 seconds was transformed into a marked peristaltic contraction 

 upwards and downwards. We have frequently, in excised and 

 still living (warmed) pieces of intestine, observed the peristaltic 

 or anti- peristaltic progress of the contraction of the circular 



