Development of the Jugular Lymph Sacs. 287 
tap of evacuation through its union with a dorsal tributary of the 
precardinal. 
3. The gradual reduction in the number of early multiple 
connections which exist between the veno-lymphatic plexus and 
the veins. 
4. The complete separation of the dorsal plexus from the 
promontory on the right side and the persistence of a single point 
of connection on the left through the subclavian approach (Tap 
C). 
5. The persistence of a single point of connection between the 
caudal division of the ventral veno-lymphatic plexus and the 
promontory on both sides of the embryo (Tap 6), this represent- 
ing the primary promontorial connection of the para-precardinal 
channel and its associated veno-lymphatic component of precar- 
dinal tributary 4. 
6. The presence of two closed sacs on the right side, one with- 
out blood corpuscles, which have become detached from the para- 
precardinal channel and its associated veno-lymphatic component 
of precardinal tributary 4. 
Series 77, 11”” Embryo 
Figs. 51 and 52 
1. Forward extension of the dorsal veno-lymphatic plexus 
and the establishment on both sides of the embryo of an anterior 
tap of evacuation. 
2. Fusion of cephalic division of ventral veno-lymphatic 
plexus with anterior end of dorsal plexus. 
3. With the exception of the anterior tap of evacuation no 
communication exists between the straight segment of the pre- 
cardinal and the veno-lymphatic plexus. 
4. Two points of communication between the general veno- 
lymphatic plexus and the promontory are present which, in 
the entire series of embryos examined, appear the last to be 
given up, as well as the most constant in character; one is with the 
dorsal veno-ly mphatie plexus through the subclavian approach (Tap 
C), the other with the caudal division of the ventral plexus through 
the jugular approach (Tap B). These two points of communica- 
