72 



Florence B. Sabin. 



VIII. VAKIOUS OTHER THEORIES IN REGARD TO THE 

 ORIGIN AND DEVELOPMENT OF THE LYMPHATIC 



SYSTEM. 



1. Mayer-Lewis Anlagen. 

 In the preceding pages has been given a consistent account of how 

 the lymphatic system buds off from the veins and gradually invades 

 the body. The places where the lymphatics bud off vary in different 

 forms; in the amphibia and reptiles, and in the case of the posterior 

 lymph hearts in birds the primary lymph sacs lie in the myotomes and 

 receive striated muscle and become lymph hearts. In the higher forms 

 the anterior lymphatics come from the anterior cardinal vein and its 

 branches, the caudal lymphatics do not develop (mammals) and the 



Pig. 18. — Diagram to show the theory of Ranvier and myself that the 

 lymphatics arise from the veins. The veins are striped, the lymphatics 

 dotted. 



posterior lymphatics come from the vena cava and renal veins. From 

 these points of origin can be traced all the lymphatics of the body 

 down to the ultimate capillaries. 



This theory has not been developed without opposition. In section 

 I it was made clear that the first theory of the origin of the lymphatics 

 was that they arose in the periphery as dilated tissue spaces and grew 

 towards the center, Gulland (39). This was questioned by Sala 

 (137), showing that the first lymphatics in birds were against the 

 veins, and by my proving in 1902 that the jugular lymphatics are 

 the first lymphatics in mammals and that they bud off from the 

 anterior cardinal veins. Thus I substituted for the theories shown in 



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