170 JOHN STEPHENS LATTA 



that the submucosal lymphatics of the intestine do not serve 

 primarily in the transportation of chyle, but are, in a certain 

 sense, related to the formation of follicles. As evidence of this 

 he finds the first large groups of lymphocytes arranged about 

 vessels, ''as in lymph glands, and the tonsils of the mouth." 



In the present study of the region of the intestinal tonsils, 

 it was found that in the newborn animals and late fetuses before 

 there were any evidences of lymphatic tissue and before absorp- 

 tion of food had started, that lymph vessels had formed quite 

 extensively in the submucosa, making quite a rich submucosal 

 plexus, such as the plexuses Gulland, Sabin, and Saxen found in 

 regions of developing lymphatic nodes. This plexus connects 

 with the retroperitoneal sac and through it with the thoracic duct 

 and the venous system by means of lymphatics of the mesentery. 

 (Heuer, '09; Sabin, '14). When the lacteals and the mucosal 

 plexus form, they become connected with the submucosal plexus, 

 the latter then becoming a part of the system for the trans- 

 portation of chyle. None of the lymphatic vessels, then, which 

 are found in the wall of the intestine are connected with any 

 entering vessels, the lymph flow being all directed away from 

 the intestine. Consequently, any lymphocytes which may be 

 found in the lymph vessels in the intestine wall have probably 

 entered them from the surrounding lymphatic tissue rather 

 than have been carried in by the lymph stream. Thus the 

 theory that lymphocytes of the intestinal tonsillar lymphatic 

 tissue have been carried in and left by the lymph stream seems 

 highly improbable. 



It is noted, however, that there is also a close relationship 

 between the blood capillaries of the mucosa and submucosa and 

 the developing lymphatic tissue of the intestine. The first 

 lymphocytes to appear, however, bear very little or no definite 

 relation to the blood vessels, and only after they become present 

 in considerable numbers do they appear to gather in clumps 

 about the blood capillaries. This seems to the writer to indicate 

 that the part played by the blood vessels should be considered 

 as a nutritive one rather than a source of lymphocytes, as was 

 thought by Gulland. 



