543 



In a former communication to the Association of American Ana- 

 tomists Huntington and the writer described the presence of oval or 

 spindle-shaped spaces, not only along the course of the azygos but 

 also along the external and internal jugular, cephalic and subclavian 

 veins, and stated that the main lymph channels which follow these 

 veins in the adult cat were formed through a confluence of these spaces. 

 Also, since these spaces do not appear to communicate with the veins 

 and lie in close contact with their intima, they regarded them as being 

 formed as the result of a condensation and recession of the main 

 venous channels and, in such a way, that as the intima recedes, 

 following the blood current, these spaces increase in size and number 

 and later become confluent. 



The difficulty involved in following the genesis of these spaces is 

 naturally considerable and, without being able to trace their origin back 

 to the venous system, the only inference one can draw is that they 

 are developed independently of the latter. It is now clear to the 

 writer, however, so far as the thoracic and right lymphatic ducts are 

 concerned, that the former view, concerning the actual origin of these 

 spaces, is no longer tenable. In the writer's estimation, however, the 

 view that the main lymphatic channels are formed through a confluence 

 of isolated and independent spaces still holds good, at least, so far as 

 the development of the thoracic and right lymphatic ducts is concerned. 



A more detailed account of the development of the thoracic and 

 right lymphatic ducts is reserved for a future publication. 



March 16, 1908. 



lymphatics develop along the azygos veins, apparently as independent 

 outgrowths, and that the lymphatics along the aorta (thoracic ducts) 

 appear to be derived in part from the jugular sacs, the azygos and 

 subcardinal veins. 



