/ • net /.'. Sabin. 



jugular lymph sac in the pig it is clear in Sg. 16 that 

 i lymph glands develop: ill the deep jugular lymph node which 

 - the pharynx an •• code in the p triangli 



bich drains the -kin of the anterior part of the body. A. II. 



I has shown that these two glands are single glands in 

 the adult pig and that tl me the largesl of all the cervical 

 ads. In tlic human embryo these two glands are represented by 

 ads, the glands of the posterior triangle and the di 

 jugular glands. In the human embryo also the group of deep axillary 

 glands comes from an extension of the jugular sac along the primitive 

 ulnar vein and hence they are primary lymph glands. Thus the pri- 

 mary nodes for the anterior pari of the bodj are i 1 i deep jugular nod< -. 

 the nodes of the posterior tria I) the axillary nodes. The 

 ation of the primary lymph gland, both to the various structures 

 of tlif neck and to the stalk of the jugular sac, that is, to the jugular 

 lymph trunk-, is shown especially well in fig. K from pig 7.5 cm. 

 long. The anterior curvature and the sac stalk lit 1 behind, that 

 medial to the sternocleidomastoid muscle. Of the primary nodes in 

 the neck the deep jugular nodes drain a restricted area, nam<fly, I 

 pharynx and nose; the axillary lymph nodes drain the arm. and the 

 larg of the posterior triangle drains all the rest of the head, fa 

 neck and thorax, either directly or through the superficial cervical 

 cus. The nodes of the superficial cervical plexus are secondary to 

 the primary lymph sac nodes. It has been brought out that these 

 ups of lymphatics do not remain distinct as thej arise, Imt all be- 

 e connected with each other through anasl ses of the lymph 



From the retroperitoneal sac develop the retroperitoneal lymph 

 nod< -. From the iliac sacs in the pig there is a (ham of small nodes 

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

 the bifurcation of the aorta. These are primary iliac nod,'-. Itorsal 

 to ! ta is a chain of nodes from the lower end of the cistema 



chyli to the bifurcation of the aorta. Thus the renal lymphatics give 

 ri.-e to three groups of primary lymphatic glands: (1) prae-aortic or 

 retroperitoneal, (2) symmetrical iliac nodes lateral to the aorta, and 

 i :: i prae-vertebral nodes dorsal to the aorta. 



'I ' • idary lymphatic nodes develop along the lymphatic vessels. 



The most extensive group of secondary nodes in the enihryo pig is the 

 one which comes from the superficial cervical plexus along the external 



