MOVEMENTS OF THE INTESTINES. 



327 



originating in the intestine or elsewhere and transmitted reflexly 

 through the central nervous system. 



As is well known, the muscular wall of the small intestine consists 

 of two layers of unstriated muscular fibres separated by a thin layer of 

 connective tissue, in which is embedded a rich plexus of ganglion cells 

 and non-medullated nerve fibres, known as Auerbach's plexus. Fine 

 fibres from this plexus form networks round the individual fibres of the 

 two layers. These layers are separated from the mucous membrane by the 

 submucosa, a tough, fibrous membrane which, according to Mall, 1 deter- 

 mines the limit of distension of the intestine. The two muscular coats 

 are so closely bound together, that it is difficult, by inspection, to deter- 

 mine whether any given change of form of the intestine is caused by a 

 relaxation of one coat or by a contraction of the other coat. It is 

 possible, however, to record the contractions of the two coats inde- 

 pendently ; when it is found that they nearly always contract simul- 

 taneously, the function of the longitudinal coat being to aid the contrac- 

 tion of the circular, and not to assist in the relaxation of the intestine. 



The 

 traction 



con- 

 of 



the longitud- 

 inal or circu- 

 lar coats may 

 be conveni- 

 ently regis- 

 tered by 

 means of the 

 enterograph 

 (Fig. 185). 



In a brass 

 plate aa, two 

 steel needles, 

 b and c, are 

 fixed in a 

 slot ; b can 

 be shifted 

 nearer to or 

 farther from c 

 by loosening 

 its fixing 



Intestt rte 



Fig. 185. 



prolonged through the slot, and revolves as a lever round the axis dd. The 

 upper end c is fastened by a thread to the disc on the rubber of the tambour e, 

 which communicates by a tube/, with a piston recorder. The lower ends of h 

 and c are pierced with holes. Through these holes pass fine threads, which are 

 carried by a needle through the outer layers of the intestinal wall, and fastened. 

 The muscle fibres running from b to c can only contract by pulling c towards 

 b. This causes a movement of the upper end of c in the opposite direction, 

 and a consequent pull on the membrane of the tambour, which is registered by 

 the piston recorder. The distance of e from c' and the tension on the muscle 

 fibres between b and c can be regulated by means of the screw x, or roughly 

 by moving the tambour in the slot z. 



The contractions of the circular coat alone can be registered by introducing 

 an indiarubber bulla, which is slightly distended with air or water, into the 

 interior of the intestine through an opening in the free border, and connecting 

 1 Johns Hojikius IIos]). Hep., Baltimore, 1896, vol. i. p. 37. 



