Lymphatics in Small Intestine of the Pig. 101 



In Fig. 3 is shown a lymphatic injection of a pig 3.5 cm. long. 

 At this stage the sac is readily injected either through the thoracic 

 duct or directly. It is diamond shape with a slight indentation op- 

 posite the suprarenal bodies. This indentation indicates a division 

 of the sac into two portions, an anterior portion which, as is seen 

 in Fig. 4, sends vessels to the stomach, spleen and duodenum 

 while the ducts for the intestine come from the posterior portion. 

 At this stage, namely, at 3.5 cm., there are a few vessels extending 

 on to the suprarenal bodies, as well as numerous blunt processes 

 to the Wolffian body. It is especially to be noted that the sac is 

 a solid mass, in the injected specimen, that is, it has a single cavity 

 in contrast to the later stage of Fig. 7, where the sac is broken up 

 into a mass of vessels making the anlage of a lymph node or a 

 group of nodes. 



In Fig. 4 is shown an injection of an embryo 4.5 cm. long. 

 This stage is particularly interesting to us, for it shows the lym- 

 phatics extending into the mesentery. The thoracic duct is plain, 

 and there is a vessel running to the heart, as well as a back flow 

 from the point of injection to the jugular lymph sac. Below the 

 diaphragm, the stomach has been pulled up and the spleen turned 

 over to the left to show the lymphatics passing to its dorsal border. 

 The mesenteric sac is now considerably larger, measuring 5 by 4 

 mm. From its anterior border three groups of vessels are seen, 

 one to the spleen, a large group which reaches the stomach wall, and 

 the third group which pases on to the duodenum. In the mesentery 

 of the coil of the lower end of the duodenum, the vessels form a 

 beautiful plexus and have reached the mesenteric border of the gut. 

 The sac itself, which still retains its character as a large sac, is 

 connected with the thoracic duct in three places, one, the principal 

 group of several ducts opposite the hilum of the kidney which is 

 the primary connection seen in sections at 3 cm., as shown in 

 Bsetjer's Fig. 9 ; secondly, a small duct which connects the 

 anterior end of the sac with the thoracic duct; this duct nms 

 just anterior to the suprarenal body; and thirdly, an anastomosis 

 between the posterior end of the retroperitoneal sac and the pos- 

 terior lymph sac. These relations are all shown in Fig. 5, 



