ON THE PROBLEM OF LYMPH FLOW BETWEEN 



CAPILLARIES OF THE BLOOD-VASCULAR 



SYSTEM AND BLINDLY-ENDING 



CAPILLARIES OF THE 



LYMPHATICS 



I. INTRODUCTION 



During the last twenty years, the writer has been specially 

 interested in the morphology and the physiology of the lym- 

 phatic system. In the course of his investigations several 

 problems have presented themselves. Among these is an 

 inquiry into the causes of oedema, concerning which two 

 papers have already been published. 1 Another problem con- 

 cerned a possible provisional arrangement of the embryonic 

 lymphatic system, by which could be explained the manner 

 in which a centripetal lymph flow toward the venous circu- 

 lation from the interstitial spaces could be controlled and 

 regulated until the lymph could reach the venous circulation. 



It is now well known that the anlagen of the lymphatic 

 system do not make their appearance in the embryo until 

 after the blood-vascular channels have been established. As 

 soon, however, as the latter begin to function, lymph neces- 

 sarily begins to collect in the interstitial spaces of the embryo, 

 and accumulates there until it is subsequently collected by 

 the newly formed set of blindly ending vessels, the lymphatics, 

 by which it is conveyed to the venous circulation. 



One of the salient facts observed in the development of the 

 vascular system is that the main channels, both haemal and 

 lymphatic, develop in loco from mesenchyme and are formed 



1 McOlure, C. F. W. 1919 On the experimental production of oedema in larval 

 and adult anura. Jour. Gen. Physiol., vol. I. 



1925 An experimental analysis of oedema in the frog, with 



especial reference to the oedema in red-leg disease. Amer. Anat. Mem., no. 12. 



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