190 George 8. Huntington and Charles F. W. McClure. 
the adult human subject, and the investigations of MeClure and 
Silvester show that this arrangement is found in a very large 
series of mammalian forms. As far as our own observations on 
the cat and in man are concerned, we have drawn the following 
conclusions: 
(1) The Saccus lymphaticus jugularis is a distinct adult 
mammalian structure, connected on the one hand with the syste- 
mic lymphatic trunks of the entire body, and on the other with 
the systemic veins, and transmitting the flow of lymph from the 
lymphatic into the venous system. 
(2) Serving in this manner as the lymphatico-venous connect- 
ing channel, the jugular sac maintains throughout adult life its 
character as a receptacle of distinct and relatively large caliber, 
and is not extensively involved in lymph node formation. 
(3) The current anatomical descriptions of the termination 
of the ‘‘thoracic duct’ in the ‘“‘jugulo-subclavian angle,’’ or, 
according to variations, in the individual veins of this conflu- 
ence, should be modified to correspond to the actual conditions 
above described. 
(4) It is scarcely necessary to call attention to the surgical 
importance of the jugular sac in man. In cases of large and 
multilocular sacs the structure might be easily wounded in opera- 
tions involving the jugulo-subelavian region. On the other 
hand, under these circumstances, it should be possible to close 
the wound successfully by suture of the walls of the sac, without 
interfering with lymphatic return through the thoracic duct and 
the other tributaries of the sac. 
ON THE ESTABLISHMENT OF THE LYMPHATICO-VENOUS CON- 
NECTIONS OF THE ADULT. 
One of the greatest difficulties encountered in our investigation 
was the deterinination of the exact manner in which the perma- 
nent lymphatico-venous connections are established in the adult. 
Do the veno-lymphatic anlages of the jugular lymph saes under- 
go a complete separation from the main veins and then, after 
fusing to form the jugular sacs, secondarily rejoin the veins: at 
either one of the two or at both of the points at which a communi- 
