188 George 8. Huntington and Charles F. W. McClure. 
munication with thé veins, are filled with blood and appear to 
function as veins, while the latter apparently do not. 
THE RETENTION OF THE EMBRYONIC JUGULAR LYMPH SAC AS AN 
ADULT STRUCTURE AND THE GENERAL CHARACTER OF THE 
LYMPH ATICO-VENOUS CONNECTIONS IN THE ADULT CAT. 
A detailed description of the variable conditions manifested by 
the lymphatics of the neck region in the adult cat is a subject upon 
which one of the writers (Huntington) is at present engaged. 
The question concerning the fundamental character of the com- 
munications which exist between the lymphatics and the veins 
on each side of the body in the adult cat, as well as that concerning 
the persistence of the embryonic jugular lymph sac in the adult, 
have, however, claimed our attention. ' 
An examination of a large number of adult cats!® has shown 
that a cemmunication between the lymphatics and the systemic 
veins may normally occur, on each side of the body, at either one 
of two or at two typical districts which correspond, approximately, 
to the angles of confluence formed by the union of the internal 
and external jugular" (common jugular angle) and of the com- 
mon jugular and the subclavian veins (jugulo-subclavian angle), 
respectively. We have found that neither one of these two angles 
of venous confluence predominates as the place of communication, 
but that either one of the two or both may serve in this capacity, 
and for this reason both districts must be regarded as constituting 
the normal points at which in the adult cat the lymphatics 
communicate with the systemic veins. 
The three forms of communication normally met with in the 
adult cat are shown in fig. 1? (left side) in which a communication 
10 Figs. 1, 2 and 3 are selected from a series of 180 lymphatic injections of the 
adult cat (Nos. 13, 26 and 40), which form the basis of a forthcoming publication 
on lymphatie variation in this species. They are reproduced here to define the 
fundamental plan of the adult connections of the jugular lymph sacs with the veins. 
11 'This vein, strictly speaking, is acommon jugular vein in the cat but on account 
of its large size, as compared with the internal jugular, is usually spoken of as the 
external jugular vein, of which the internal jugular is a tributary. 
” All of the figures referred to in this paper are arranged in sequence on 
plates and a description of the same, preceding the plates, may be found on 
page 308, 
