Lymphatics in Small Intestine of the Pig. 



107 



one half around the intestine, before penetrating the muscle coats, 

 as shown in Fig. 8. In the latter case, by the branching of this 

 vessel, a subperitoneal plexus may develop, a consideration of which 

 will be taken up later. 



The variations in the course of the lymphatic vessels above de- 

 scribed may be seen in any part of the intestine and in all stages 

 of embryos where lymphatics have entered the intestine as well as 



Fig. 8. — Injected lymphatics in the duodenum of a pig embryo 8.7 cm. long 

 to show the entrance of the lymphatics into the submucosa, the submucosal 

 plexus, and the beginning of the mucosal vessels. C. m., circular muscle ; 1. m., 

 longitudinal muscle; m. 1. n., mesenteric lymph node. 



in the new-bom and adult pig. The same relation is seen in an 

 older embryo, 16 cm. long, in Fig. 14. In injecting the lymphatics 

 of the intestine of the new-born or adult pig, the variations in the 

 course of the large collecting trunks through the intestinal wall to 

 reach the mesentery is frequently observed. 



This variation in the course of the lymph vessels through the 

 bowel wall is dependent upon the distribution of the blood vessels. 

 It was shovna in tracing the growth of the lymphatics through the 



