80 



Dr. W. R. Gowers on the Automatic [Mar. 15, 



sphincter. The lower end of this line represents, therefore, the degree 

 of the previous contraction of the sphincter, and corresponds to the top 

 of the line (a) in fig. 1. The slight initial rise (c) precedes a considerable 

 fall (d), and is succeeded by a slow rise, in which there are secondary- 

 waves of rhythmical variation (eee). No such variation could be traced 

 in the continuous contraction which followed. 



Goltz* observed that in dogs, after division of the dorsal cord, a 

 rhythmical action was caused by the presence within the sphincter of any 

 foreign body. In man it does not appear that the presence of an unirri- 

 tating foreign body within the anus, provided it is kept still, constitutes 

 stimulation or excites any reflex action. No rhythmical variations were, 

 as a rule, observed in the tonic contraction. In one case of disease of the 

 dorsal spinal cord, however, the mere presence of the instrument caused 

 sometimes a lengthened inhibition, at the end of which some rhyth- 

 mical contraction occurred. But it was found that, in every case, the 

 continuous injection of a jet of air into the rectum developed, very 

 uniformly, a rhythmical action. The rapid fall which occurred imme- 

 diately after the commencement of the injection was succeeded by a 

 rather quick rise, followed by another fall, and then a corresponding rise, 

 and so on in successive alternations. Thus a continuous series of nearly 

 uniform curves was obtained (figs. 4, 5, 6). The height reached by the 

 lever in these variations was in some instances the same as that of its 

 continuous contraction, but in other cases it was less high. The cause 

 of the rhythmical variation appeared to be, in part at least, the alternating 

 accumulation of the air within and its escape from the rectum during the 

 contraction and relaxation of the sphincter, the accumulation causing the 

 inhibition of the sphincter, which permitted the escape of air. A differ- 

 ence noticeable in the form of these curves will be considered in speaking 

 of their duration. 



In some instances the rhythmical action was long in being developed, 

 the first effect of the continuous injection being a complete inhibition of 

 considerable length, succeeded by the intermitting contractions. 



Goltz observed that a powerful sensory impression on the hind legs of 

 a dog inhibited the rhythmical contractions of the sphincter. In the case 

 of injury to the sacral nerves no such inhibition could be obtained by 

 strong faradic stimulation of the skin of the lower part of the abdomen, 

 on which sensation was intact. 



The effects of a voluntary effort, a sigh, and a cough were observed to 

 ascertain if there was any consentaneous contraction of the sphincter ; 

 but none could be observed. 



Careful measurements were made of the duration of the several events 

 in the reflex action above described. 



On every form of stimulation it was found that a period elapsed after 

 the commencement of the stimulation before there was any change in 

 * Pfiiiger's Archiv, vol. -viii. 1874, p. 479. 



