16 DEVELOPMENT OF THE SYSTEMIC LYMPHATIC VESSELS 



(3) The mode of union with each other of the two components 

 just enumerated, and the resulting estabhshment of a continuous 

 centripetal lymphatic vascular system, with definite and constant 

 terminals in the venous trunks. The first part of this work has 

 been completed in conjunction with Prof. C. F. W. McClure 

 of Princeton University. The results of our joint investigation 

 on the development and structure of the jugular lymph sacs 

 of the Cat have been published in a preliminary account. ^^ The 

 details, with critical anal^^sis of a large series of embryos, and 

 illustrations of the reconstructions of all the important stages, 

 are given in an extensive paper recently published." 



In these publications McClure and I have definitely demon- 

 strated the fact that in the embryo of the cat the jugular lymph 

 sacs develop as a small, but vitally important, part of the entire 

 lymphatic system, directly from the pre- and postcardinal veins 

 and their tributary plexuses, near to and including their Cu- 

 vierian junction. 



The genesis of the jugular lymph sacs and their share in the 

 adult organization having been thus definitely established in 

 detail, I intend to follow independently the second postulate 

 (jf the theory of the composite character of the adult mammalian 

 lymphatic system above outlined (VI), and to show that the 

 jugidar lymph sacs, of direct venous origin, constitute the links 

 uniting the haemal vascular system and the general system of 

 the hjmphatic vessels, the latter developed independently of the 

 veins, by the confluence of intercellular mesenchymal spaces 

 surrounding, for the most part, the embryonic venous channels, 

 but in no sense derived from the same. 



MATERIAL 



For the reasons stated above I have chiefly used the embryos 

 of J,he domestic cat. Of these I have examined the following 

 107 individual embryos in complete serial sections: 



*■' C. S. HuTitiiiKton and C. F. W. McClure: "The Anatomy and Development 

 of the Jugular Lymph Sacs in the Domestic Cat." A7iat. Record, vol. ii, 1908 

 ■pp. 1 18. 



" American Jovr. of Anal., vol. x, no. 2, April, 1910, pp. 177 to 31 1 with 67 figures. 



