MOVEMENTS OF THE ALIMENTARY CANAL. 641 



ods. The first noteworthy contributions to this subject were 

 those made in this country by Beaumont in his famous observations 

 upon Alexis St. Martin, the Canadian voyageur, who had a per- 

 manent fistulous opening in his stomach as the result of a gunshot 

 wound.* In recent years the subject has been studied with great 

 success by means of the X-rays,f on the excised stomach, J and by 

 means of tambours or sounds introduced into the stomach to meas- 

 ure the pressure changes. These researches all unite in em- 

 phasizing one fundamental point, namely, that the fundic end 

 of the stomach is not actively concerned in these movements, but 

 serves rather as a reservoir for retaining the bulk of the food, while 

 the muscular pyloric region is the apparatus which triturates and 

 macerates the food and forces it out from time to time into the 

 duodenum. According to the observations made with the X-ray 

 apparatus, movements begin a few minutes after the entrance of 

 food into the stomach. Small contractions start in the middle 

 region of the stomach and run toward the pylorus. These moving 

 waves of contraction appear at regular intervals. The pyloric 

 portion becomes lengthened and it may be noticed that in this 

 region the peristaltic waves become more and more forcible as 

 digestion progresses. These running waves of contraction serve 

 to press the stomach contents against the pylorus. According to 

 Cannon, they occur in the cat at intervals of 10 sec. and each 

 wave requires about 20 sec. to reach the pylorus. According to 

 Beaumont's observations, the contraction waves follow at longer 

 intervals in man (2 to 3 min.). The obvious result of these 

 movements is to mix the food thoroughly in the intermediate 

 and pyloric portions of the stomach with the acid gastric juice 

 and to reduce it to a thin, liquid mass, the chyme. At certain 

 intervals the pyloric sphincter relaxes and the contraction wave 

 squeezes some of the fluid contents into the duodenum with 

 considerable force. The mechanism controlling the relaxation 

 of this sphincter is obscure. It does not occur with the ap- 

 proach of each contraction wave, but at irregular intervals. 

 Cannon connects it with the consistency of the food. Solid 

 objects forced against the pylorus prevent relaxation and retard 

 the passage of the chyme into the intestine. When liquid food 

 alone is taken into the stomach numerous observations made by 

 means of intestinal fistulas show that the material is forced into 

 the duodenum within a few minutes. According to this description, 



* See Osier, "Journal of the American Medical Association," Nov. 15, 

 1902, for life of Beaumont and account of his work. 



t See Cannon, "American Journal of Physiology," 1, 359, 1898; and 

 Roux and Balthazard, "Archives de Physiologic," 10, 85, 1898. 



t Hofmeister and Schiitz, loc. cit. 



Moritz, " Zeitschrift f . Biologic, " 32, 359, 1895. 

 41 



