ON THE DEVELOPMENT OF THE LYMPHATICS IN THE 

 STOMACH OF THE EMBBYO PIG, 



The work of Dr. Mall (1896) on the anatomy of the lymphatics of the wall 

 of the stomach has established the plexiform arrangement of these vessels and their 

 relation to the other structures of this organ. By dissecting the stomachs of dogs in 

 which the lymphatics had been injected, and by reconstructions of such dissections, 

 the entire organ was shown to be supplied with four definite, homogeneous plexuses. 

 The most delicate of these, and the one most intimately related to the lining of the 

 stomach, is the mucosal plexus. It lies in the mucosa at the base of the gastric 

 glands just external to the muscularis mucosse and receives branches which lie 

 between the glands and extend out as far as the gastric pits. Owing to the delicacy 

 of these vessels and the fact that valves prevent their injection from the main 

 plexus of the submucosa, any attempt at complete injection is attended with much 

 difficulty. As a matter of fact, the mucosal vessels can be injected in the adult 

 only by direct puncture, which means that the needle must actually pass through the 

 muscularis mucosa? and enter the narrow zone between it and the base of the gland ; 

 it can be readily seen that such an exact placing of the needle occurs only by chance. 

 However, th( best specimens obtainable indicate clearly that the lymphatics 

 between the glands communicate directly with this delicate, homogeneous plexus 

 lying at the base of the glands of the mucosa. 



Proceeding through the wall of the stomach toward its serous surface, the first 

 plexus of the submucosa is encountered. This consists of a single layer of lym- 

 phatics, just outside the muscularis mucosse, and forms the connecting link between 

 the mucosal plexus, just described, and the main plexus of the submucosa, the 

 principal plexus of the wall of the stomach. This main plexus is a dense mass of 

 vessels which practically fills the submucosa and is composed of several layers of 

 large, tortuous, thickly arranged lymphatics. Springing from it are numerous 

 slender vessels which traverse the muscular coats of the stomach, forming a coarse 

 plexus between them, and are gathered together on the surface of the stomach into 

 the subserous plexus, a dense, single layer of lymphatics situated just beneath the 

 peritoneal covering of the organ. 



The work of Dr. Mall extended that of Sappey, Teichmann, and Loven. It 

 may be seen, therefore, that the anatomy of the lymphatic vessels in the wall of 

 the adult stomach is well known. The pathways of lymphatic drainage from this 

 organ, however, are not so clearly understood. All investigations along this line 

 have consisted in partial injections of the adult stomach. In the present experi- 

 ments the direction of flow of the injection mass from different points was noted and 

 from the information so gained the direction of normal lymphatic drainage, in vivo, 

 is inferred. 



The most extensive work of this kind has been done by Cuneo. By injecting 

 colored substances directly into the main plexus of the submucosa, and watching its 



