170 ELECTRO-PHYSIOLOGY CHAP. 



the peristaltic movements of smooth muscular organs, as we know 

 from experiment, are so easily disturbed and affected by a variety 

 of data. This applies in particular, e.g., to the movements of the 

 intestine, which Engelmann treats as analogous with the peristalsis 

 of the ureter (29). Apart from the richly-developed plexuses of 

 nerves and ganglia in the wall of the intestine, and its far more 

 complex development of muscular layers, the structure of the two 

 organs shows such a fundamental agreement that we are justified 

 in assuming a priori that the conductivity of excitation and 

 contingent peristalsis are derived in both cases from the same 

 principle. In this connection we have especially weighty evidence 

 in the fact that a wave of contraction starting from any point in 

 the continuity of the intestine is transmitted under favourable 

 conditions to either side of the point of excitation, just as it is in 

 the integument of the ureter, i.e. peristaltically and anti- 

 peristaltically. This is not, indeed, the case invariably nor, 

 above all, in every animal. Thus in the frog's intestine, even 

 under the most favourable conditions of excitability (in 

 summer with a high temperature), local excitation will scarcely 

 ever produce anything more than localised constriction, or at 

 most spreading over a few millimeters. The reaction is much 

 more easily provoked on the living, warm-blooded intestine, e.g., 

 of cat or dog, which has the farther advantage that on opening 

 the abdomen the intestines are usually quiescent, which is not to 

 the same degree the case with the rabbit. But even here the 

 observations required are not nearly so certain as in the ureter. 

 It would rather seem as though a certain condition of excitability 

 in the intestine was essential to the success of the experiment. 

 According to Engelmann this is best secured when the animal is 

 killed by bleeding from the large cervical vessels. If the belly is 

 opened soon after the last respiration, the intestines are either 

 in the required state, or pass into it shortly after. If the 

 muscular coat of a loop of the small intestine is then mechanically 

 excited at any point (by pinching with forceps), Engelmann finds 

 a vigorous contraction of the circular layer of fibres, which 

 spreads outwards from the excited spot in a peristaltic and anti- 

 peristaltic direction over the whole small intestine, at a low 

 velocity of about 40 mm. per sec. Engelmann gets the same 

 results with excitation of the large intestine. While at the first 

 stimulus the contraction is pronounced throughout its entire 



