1" ■ n, . /.'. Sabin. 



rHE Arguments fob the Venous Origin of the 

 Lymph mi System. 



I shall now take up the proof of the theory thai the lymphatic 

 i- derived from the veno ■ m. and will subsequently 



analyze the <>p|»>»in;: theory, which, in its most recenl from, 

 lymphal addition of tissue spaces (Kampmeier 66 and 



essentia] elements in the establishing of the venous origin of 

 the lymphatics have been (1) the proof that lymphatic capillai 



x by the sprouting of their endothelial wall and not by the addition 

 or hollowing out of connective tissui This argumenj iwn 



the method of growth by sprouting. (2) The proof that lym- 

 phatics gradually invade the body from 1 1 periphery, establishing 

 point of lymphatic and non-lymphatic zones. This means that 

 the main ducts grow as capillaries by the same method as the per- 

 ipheral capillaries. This argument is known as the one of lymphatic 

 and non-lymphatic zones. (3) Thai the original lymphatic ducts 



bud off din om the veins. This is known as tit igin of the 



kin; v budding. 



Thus the study involves three elements: The nature of the lym- 

 phatic capillary, the nature of the lymphatic ducts, and the nature of 

 the first lymphatics or the lymph sacs. Bach one of these three lines of 

 proof involves the stud} of endothelium; the first lymphatics are buds 

 ■ adothelial lining of the veins; these endothelial buds invade 

 body down to the ultimate capillaries by the cell division of their 

 i ndothelial wall. 



A. GROWTH in LYMPHATIC CAPILLARIES I'.Y SPROl KNG. 



A study of the method of growth of lymphatic capillaries is neces- 

 sarily ass ted with the study of the method of growth of bl I 



Ear back as the time <>t" Schwann (Ki'M. who first 

 Baw the capillaries in the living tadpole's tail and who vaguelj dis- 

 tinguished those which carried blood from those which had no cor- 

 puscles, there is a clear recognition that the two forms of capillaries 

 grow by the same method. This method Schwann thought to be by 

 the addition of hollow connective tissue cells. 



in growth by Bprouting was introduced quite recently by His, 

 but the first description of the process dates back to the year 1844, to 



