66 



Anterior lymphatics of body wall 



The anterior lymphatics of the body wall are the largest 

 of the series and encircle the anterior abdominal wall in a 

 much distended plexus, with branches extending forward into 

 the tissues superficial to the greatly expanded branchial cav- 

 ity (fig. 30). The afferent ducts are joined by the jugular 

 lymphatic (fig. 30) as they come together over the anterior 

 lymph heart (partly hiding it) to form a large vessel which 

 also receives the proximal end of the lateral lymphatic from 

 behind (fig. 30) and opens into the heart through its dorsal 

 wall (Dsl.R.D.). 



In addition to receiving the collecting ducts from the sys- 

 tem of the anterior and posterior lymphatics, the dorsal ves- 

 sel is entered by tributaries from the lymphatics of the internal 

 (visceral) system and those from the dorsal structures. The 

 latter are best shown in dorsal view (fig. 31), where the affer- 

 ent ducts from the tissues around the nose and eyes, and over 

 the brain and cord, may be traced to this reception duct or 

 chamber (also figs. 27, 27b, 30; Dsl.R.D.), which thus serves 

 as an atrium for the heart. 



Internal visceral lymphatics 



Hoyer has described the internal or visceral lymphatics for 

 frog larvae recently in his memoir on the "Comparative 

 Anatomy of the Lymphatic System in Vertebrates," 1934, and 

 an excellent illustration is furnished of the abdominal system, 

 as demonstrated in an injection of a 25-mm. larva of R. tempo- 

 raria. This figure ( Hoyer 's fig. 19 of '34) is reproduced here 

 much reduced in size (text fig. B, p. 67), since it gives a com- 

 plete picture of the lymphatics in the abdomen like that in my 

 own injections of the 18-mm. larva of R. palustris. However, 

 my injections add visceral lymph vessels, anteriorly in the 

 head (pharyngeal duct, etc.). The main features of the ab- 

 dominal visceral system may be readily traced in Hoyer 's 

 figure (text fig. B of this paper). Two central ducts, the sub- 

 vertebral lymph trunks, lie parallel along the mid-dorsal line 

 on each side of the aorta, running forward to the point of 



