37 



lumen open into the stomach and caecum. The right arm of the lumen leads 

 to the oesophagus, the left to the hepatic duct and the central point to the 

 intestine. The three angles included between the four arms of the lumen are 

 formed by tlie walls which separate (1) the oesophagus and the intestine, 

 (2) the stomach from the caecum , and (8) the intestine tVijm the hepatic duct. 

 The openings from the oeso])hagus and trom the stomach are circular and are 

 controlled by sphincters. The openings between the caecum and the intestine , 

 and between the hepatic duct and the caecum have in addition to sphincters, 

 three adjustable valves. One valve which we may call the gastric valve , is a 

 high , hooked ridge which is situated upon the upper side of the opening from 

 the caecum to the stomach. Its concave side is directed toward the right i.e. 

 toward the stomach. A second, the intestinal valve, is formed by a high ridge 

 which arises on the upper wall of the intestine, passes backward to the opening 

 between the caecum and intestine , and then curves upward around the edge of 

 this opening forming here a quite high tubercle that projects into the caecum. 

 A. ridge arises on the left of the intestinal valve and passes backward through 

 the caeco-intestinal opening and then outward along the edge of the large partition 

 between the upper and lower lobes of the caecum. This ridge ends in a large, 

 spoon-shaped valve , the hepatic valve , which lies just behind and above the 

 opening of the hepatic duct. The concave surface of this valve is turned toward 

 the opening and the valve can be turned downward so as to cover the opening 

 and form a deep groove that . by being pi-essed against the adjacent wall . is 

 converted into a canal which leads from the hepatic duct to the intestine. By 

 the contraction of the caecal opening and the turning downward of the hepatic 

 valve, the caecum can probably be occluded from the rest of the gut while a 

 passage may remain open from the hepatic duct to the intestine and through it 

 to the stomach. 



The action of the muscles and valves above described is somewhat conjectural 

 since it is impossible to observe their normal action. However, a careful study 

 of all the data at hand leads to the inference that the following adjustments 

 probably occur. 1) The oesophagus opens into the stomach. The food is prevented 

 from passing out of the stomach by the contraction of the sphincter between 

 the stomach and the caecum. The gastric valve may possibly be drawn into the 

 opening to serve as a plug. 2) The oesophagus may open into the caecum. This 

 adjustment may be effected by the contraction of the sphincters around the 

 ventral end of the stomach and around the intestine accompanied by the relaxa- 

 tion of those around the oesophagus and caecum. 3i The stomach opens into the 

 caecum. This is accomplished by the relaxation of the sphincters around the 



