LYMPHATICS IN FROG LARVAE 65 



which in early stages extended over the ear and along the 

 hind-brain (early, figs. 26, 27 ; late, figs. 30, 31). These vessels 

 now reach far forward to drain the nasal organs, the eyes, 

 and the tissues over the brain, and connecting laterally with 

 the trunks over the heart, run back to join the original ante- 

 rior section of the dorsal plexus (figs. 30 and 31). 



Thus injections still run forward into the anterior dorsal 

 plexus to connect with the lymph heart vessels on either side, 

 though most of the fluid is now diverted behind the heart from 

 the dorsal lymphatic through connectives with the lateral 

 system. These lateral connecting vessels, now shifted dor- 

 sally to their new position, are conspicuous across the middle 

 of the back, and preserve their earlier connections with the 

 'lateral body lymphatic' on either side. Here is a contrast 

 with Hoyer's irregular dorsal plexus along the back in the 

 older (26 mm.) larva (text fig. D, p. 70) in that two or three 

 of the connectives from the median dorsal duct are usually 

 much distended, and reach to the front of the series, as pre- 

 ferred paths to the lateral trunk. No vessels, however, are 

 yet fixed at the base of the tail, as in older larvae (Hover, 

 '05, 26 mm.) for lateral diversion, right and left, of almost 

 the entire volume of lymph from behind (text fig. D, p. 70). 



Lymphatics of the body icall in late larvae irith hind limb buds 



The lymphatics of the body wall are established in late 

 larvae (R. palustris, 18 mm.) in a series of strong vessels 

 extending outward from the lateral body lymphatic, along the 

 dorsolateral areas of the back, behind the anterior lymph 

 heart. Originally short processes from the ventral component 

 of the lateral trunk (fig. 15), these outgrowths now reach far 

 out in the wall, the posterior members of the group (still from 

 the ventral lymphatic) being especially prolonged ventrally 

 to form networks in the body wall and around the rectum and 

 hind limb buds. These additional contributions from the 

 posterior body wall add greatly to the size of the lateral lym- 

 phatic as it runs forward to the anterior lymph heart. 



