450 CHARLES F. SILVESTER 



THE LYMPHATICS 



The reno-caval lymphatico-venous communications naturally 

 fall under two heads: (1) those between the intestinal lymphatic 

 trunks and the veins and; (2) those between the lymphatics from 

 the posterior extremities and lumbar regions and the veins. 

 They will be considered in this order. 



Text-fig. 1 indicates the position and number of all the reno- 

 postcaval communications found in the twenty-five individuals 

 examined. No attempt has been made in this figure to show a 

 separation between the area occupied by the mesenteric and that 

 occupied by the lumbar communications, for the reason that in 

 many instances the two areas overlap. In general, however, it 

 may be stated, that the mesenteric area of communication is 

 represented by the circles situated on the cranial border of the 

 left renal vein and on the left side of the postcava, and that the 

 remainder of the circles represent the area covered by the lum- 

 bar communications. 



1. Communications between the intestinal lymphatic trunks and 

 the veins. The communications between the intestinal lymphatic 

 trunks and the veins were found to vary in number in different 

 individuals, from one to four. In the majority of individuals two 

 main trunks are present, one situated on either side of the mesen- 

 teric artery. The trunk on the left side of the mesenteric artery 

 usually opens into the left renal vein, while the one on the right 

 side, as a rule, opens into the left side of the postcava, cranial 

 to the renal vein. The above might be designated as the typical 

 arrangement, if a typical arrangement can be said to exist, and 

 is shown in fig. 4 (Cebus hypoleucus), and fig. 8 (Saimiris 

 sciurea). In some cases the two mesenteric trunks both open 

 into the left renal vein (No. 2465, Cebus capucinus), or both open 

 into the postcava cranial to the renal vein (fig. 1, Alouata seni- 

 culus and fig. 9, Callithrix jacchus). 



Many variations from this double-trunk arrangement were met 

 with. The intestinal trunk may be single, with a single opening 

 into the postcava, as in Cebus capucinus (2481),^ and Nycti- 



* The number after the name of the species refers to the catalogue number of 

 the individual in the Princeton Collection. 



