Flort i ■ ■ /.'. Sabin. 



by which iill otl are formed, and the term ation, 



giving ll --n-.il of the splitting of the wall of a vein 



. does 1 1 ■ > i describe the actual process and is misleading, 

 ow know thai the jugular sacs bud directly from the anterior 

 cardinal ympliatics and grow by the sprouting of their endo- 



thelium. 



\- 'ia- been said, Huntington and McClure believe thai the jugular 



lymphatics come fr the veins, bul thai thej remain only as a means 



immunication between the veins and the lymphatic ducts. The 

 lymphatic ducts they mink develop in a variety of ways. 



entire o of the thod of growth of the lymphatic 



system is now concentrated on a study of the methods of growth of 

 the thoracic duct, li is probable thai the thoracic duel arises in two 

 - : thai it i- formed in mammals by an asymmetrical down- 

 growth from the left jugular sac and by a plexus which arises sym- 

 metrically from the renal veins and grows along the course of the aorta. 



second portion arises later than the first and is in the U l-filled 



I mm.) when the jugular stalk is empty. These two an] 

 grow as do .ill other lymphatics and join by the same proi i -- ;■ which 

 any lymphatic plexus is formed. 



opposing views are broughl out in two papers, oni by Hunting- 

 ton (58) and one by Kampmeier (66). Huntington describes a compli- 

 cated method of origin of the thoracic duct, including (1) a jugular 

 stalk . (2) extra-intima] spaces, and (3) general tissue spaces. Kamp- 

 meier, on the other hand, gives a clear and excellent presentation of 



the il ry of the origin of lymphatics by the addition of tissue spaces. 



1 will begin with the work of Huntington (58). His memoir on 

 the peripheral lymphatics has excellent photograpl - tions, so thai 



ii is i-ii.-v to see what he is considering as lymphatics. For example, 

 l to 9 are tissu< -. l«> to 12 are extra-intimal spi 



13 to 19 are probably lymphatics. Figure 25 shows the iliac 

 d 76. Numerous examples of extra-intimal spaces ar< shown 

 i 147. Perhaps the besl figure of an extra-intimal space 

 »o. L11A. Figun - i - 15? are h mphatii -. 

 The theory of the origin of lymphatics from extra-intimal sp 

 has been especially described in an article by Huntington in 1910 

 (55). In a diagram on page 109 be gives bis idea thai a space which 

 forms around a degenerating vein eventually includes the entire vein, 

 which then disappears so that the lymphatic is lefl with a wall of 

 nch\ me. 



