310 



THE DEVELOPMENT OF THE CHICK 



left, as in mammals; in the chick the lateral bending of the 

 stomach appears to be uncomplicated by any such rotation. The 

 curvature leaves a large space within it to the right containing 

 the meatus venosus and liver, in short, the entire median mass 

 of the septum trans versum. 



The main divisions of the intestine are marked out by their 

 position, size-relations and structure before the closure of the 

 yolk-stalk; thus on the third day the oesophagus appears as a 

 constricted portion immediately behind the pharynx, and the 

 stomach as a spindle-shaped enlargement behind the oesophagus; 

 the duodenum is indicated at the same time by the hepatic and 



Fig. 179. — Viscera of a chick embryo of 6 



days, seen from the right side. (After 



Duval.) 



All., Allantois. Au. r., Right auricle. 

 B.a., Bulbus arteriosus, c. pr., Caecal pro- 

 cesses. D. L., Loop of the duodenum. Giz., 

 Gizzard. Lg. r., Right lung. Li., Liver. 

 R., Rectum, t. R., Tubal ridge. V., Ven- 

 tricle. W. B., Wolffian body. Y. St., Yolk 

 stalk. X., Duodeno-jejunal flexure. 



pancreatic outgrowths. The form of the intestine on the sixth 

 day is illustrated in Figure 179. Behind the stomach, the intes- 

 tine forms two loops descending ventrally. The first or duodenal 

 loop is relatively slightly developed at this time, and forms an 

 open curve just beneath the right lobe of the liver. Its ascend- 

 ing limb rises to a high dorsal position jvist behind the liver, and 



