THE LYMPHATIC SYSTEM IN HUMAN EMBRYOS, WITH 



A CONSIDERATION OF THE MORPHOLOGY 



OF THE SYSTEM AS A WHOLE. 



FLORENCE R. SARIN. 

 From the Anatomical Lahoratory of the Johns Hopkins University. 



Wlien we consider the history of our knowledge of the lymphatic 

 system, it is clear that there have been two wholly different lines of 

 thought with regards to our general conceptions. To establish its 

 general morphology is the fundamental task for each of the systems 

 of the body, and upon such a general conception is based all future 

 elaboration of the system. I need only to refer to the neurone theory 

 as establishing such a foundation for our knowledge of the nervous 

 system. In connection with the lymphatic system, the idea that it 

 arises from mesenchyme spaces dominates anatomical and zoological 

 literature as is evidenced by examining most of the text books. This 

 conception is based on the work of Budge, Sala, GuUand and many 

 others. It allies the lymphatic system with tiss,ue spaces and serous 

 cavities. The other theory, which seems in a fair way to displace 

 the earlier conception, is that the lymphatics are derived from the 

 veins, that they are vascular rather than mesenchymal in origin. 

 This theory, only recently crystallized, has had an interesting evo- 

 lution; beginning with Langer and Ranvier, it has been formulated 

 and developed by a group of American anatomists. In this paper I 

 hope to add evidence for this theory and give a general picture of the 

 primitive lymphatic system as a whole. The great usefulness of 

 this theory, aside from the fact that we believe it to be true, is that 

 it gives a key by which to work out the entire development of the 

 lymphatic system down to its ultimate capillaries, and it will be 

 readily conceded that the old theory of the relation of the lymphatics 

 to the tissue spaces gave us no such point of attack. 



The American Joukxal of Axatomy. — Vol. IX, No. 1. 



