32 FATE OF PRIMARY LYMPH-SACS IN ABDOMINAL REGION OF PIG, ETC. 



The schema given on the preceding page shows graphically the relation of the 

 peripheral lymph-vessels to the primary lymphatic system. In general the lym- 

 phatics arising ventral to the aorta (the retroperitoneal sac) drain the whole or part 

 of the lung, diaphragm, liver and biliary passages, stomach, small and large intes- 

 tine, capsule of spleen, pancreas, kidney, gonad, Mullerian and Wolffian ducts, 

 umbilical cord, and Wolffian body. 



From the lymphatics arising dorso-lateral to the aorta (the iliac sacs) are 

 supplied, either wholly or in part, the diaphragm, body-wall, adrenals, kidney, 

 bladder, umbilical cord, Mullerian and Wolffian ducts, and the entirf posterior half 

 of the body. 



The structures which drain into the primary lymphatics arising both ventral 

 and dorso-lateral to the aorta are the diaphragm, kidney, and Mullerian and Wolf- 

 fian ducts. 



RELATION OF THE LYMPH-GLANDS TO THE PRIMARY AND SECONDARY LYMPHATIC 



SYSTEMS. 



Sabin (1913) has shown that the primary lymph-nodes develop from the pri- 

 mary lymph-sacs; that the pre-aortic or retroperitoneal glands develop from the 

 retroperitoneal sac; and that from the iliac sacs there arises a chain of small nodes 

 lateral to the aorta and a large group of glands on either side of the aorta opposite 

 its bifurcation. Dorsal to the aorta are the prevertebral nodes extending from the 

 lower end of the cisterna chyli to the aortic bifurcation. 



Of the secondary lymphatic nodes developing along the lymphatic vessels, she 

 states that the mesenteric glands are secondary for the retroperitoneal sac. In the 

 pig the secondary glands from the iliac sacs are simple and two in number the 

 ilio-inguinal gland (very characteristic for this animal) and the inguinal group of 

 glands. 



In this study, injections, as nearly complete as possible, were made of pig 

 embryos 20 cm. or more in length to determine what glands receive the drainage 

 from the abdominal and pelvic viscera. At this stage the glands are easily seen in 

 the gross and, by injecting the organs with india-ink, their relations to the different 

 glands can be readily demonstrated. Figure 5 is a composite drawing of an embryo 

 pig 20 cm. long, viewed from the ventral side, to show the grouping and positions of 

 the various lymph-glands relative to each other and to the different abdominal 

 organs. Those glands formed from lymphatics arising ventral to the a.orta are 

 indicated in solid color; those from lymphatics dorso-lateral to the aorta are 

 stippled. The glands along the vessels posterior to the bifurcation of the aorta, 

 however, which are in solid black, belong to the group arising from lymphatics 

 dorso-lateral to the aorta and were not stippled because of the perspective. 



In the abdomen are glands the pre-aortic extending from above the cceliac 

 axis to the bifurcation of the aorta. Anteriorly these are grouped into the cceliac 

 (fig. 5. Lymgl. ccel.) and main mesenteric glands (Lymgl. mes. sup.) and posteriorly 

 into the lumbar pre-aortics (Lymgl. praeaorticse) . Lateral to the aorta are the 



