328 MECHANISMS OF THE DIGESTIVE TRACT. 



the bulla with a recording tambour. Those of the longitudinal coat alone can 

 be registered by an ingenious contrivance devised by New, 1 consisting of two 

 glass tubes sliding the one within the other, so arranged that contractions of 

 the longitudinal coat diminish the common cavity and raise the lever of a 

 recording tambour, while contractions of the circular coat are unable to affect it. 



Nature of the intestinal movements. In order to avoid the dis- 

 turbing effects of drying and cooling on the intestines, it is best to open 

 the abdomen under a bath of warm normal saline (von Braam Houck- 

 geest). 2 The appearance of the intestines will vary according to the 

 state of the animal. If it has not received food for two or three days, 

 the intestines will be seen to be anaemic, motionless, and in a state of 

 tonic contraction. After food, however, the intestines are hyperaemic, 

 relaxed (i.e. thicker and shorter), and the various loops present the 

 swaying movements which were described by Ludwig 3 as Pendelbewe- 

 gungen. Very much the same appearance will be observed also in 



fasting animals, if both 

 splanchnic nerves have 

 been previously divided 

 (Fig. 186). 



1. Theswayingmove- 

 ments have been gener- 

 ally regarded as occa- 

 sioned by contractions of 

 the longitudinal muscles, 

 since the translatory 

 movements of the loops 



FIG. 186. Rhythmical contractions of circular coat of are more apparent than 



small intestine. A rubber balloon distended with air f >. Q n -^ . f i 



was placed in lumen of gut, and connected with a piston 



recorder. Time marking = six-second intervals. Con- calibre. If , however, W6 



traction causes upward movement of lever. record the movements of 



the intestine by con- 

 necting its interior to a piston recorder, or by inserting a small balloon, 

 which is connected with a tambour, into the lumen of the gut, we find 

 in most cases that the wall is undergoing a series of rhythmical con- 

 tractions, repeated regularly ten to thirteen times in the minute, so that 

 each individual contraction lasts from 5J to 6 seconds. This intestinal 

 rhythm is remarkably independent of external conditions, although the 

 amplitude of the contractions may be augmented or diminished. Thus, 

 distension of the intestine or of a rubber capsule in its interior causes 

 increased height of contraction, or may evoke contractions, if these were 

 previously absent. The contractions are better marked in a fed animal, 

 or when the intestines are hyperamiic. They may be diminished or 

 abolished by shutting off the arterial blood supply to the intestines. 

 They are propagated rapidly down the intestine (2 to 5 cms. per second), 

 but may originate at any point of the gut, so that an exact determina- 

 tion of their rate of propagation is very difficult. They are as well 

 marked in isolated loops as in those which retain their functional con- 

 tinuity with the rest of the intestine. Both coats of the intestine act 

 together in these contractions. In the normal intestine these waves 



1 "Proc. Physiol. Soc.," March 18, 1899, Journ. Physiol., Cambridge and London, 

 vol. xxiv. 



- Arch.f. d. ges. Physiol., Bonn, 1872, Bd. vi. S. 266. 

 3 "Lehrbuch d. Physiologie," Aufl. 2, Bd. ii. S. 615. 



