210 George 8. Huntington and Charles F. W. McClure. 
By enlargement of these fenestrae or by confluence of adjacent 
inter-reticular spaces, the terminals of the primary. tributaries 
divide into two components, a lateral veno-lymphatic (VL) and 
a medial somatic (S) element (fig. 11). 
The lateral elements, (1VL, 2VL, 3VL, in fig. 11) shift to the 
dorso-lateral circumference of the precardinal vein, the medial 
elements (18, 2S, 38, in fig. 11), conversely enter the dorso- 
medial aspect of the main channel. 
At first these two sets of components are still connected by 
transverse channels (figs. 11 and 18). 
The best example of this stage encountered in our collection is 
represented by Series 138 (ef. figs. 33, 34, 35 and 36 and the 
diagrams, figs. 18 and 37). 
Subsequently these tranverse connections are given up and then 
the dorso-lateral elements enlarge and constitute the cephalic 
division of the ventral veno-lymphatic plexus (1VL, 2VL, 3VL, 
in figs. 12 and 19), while the dorso-medial branches (18, 2S, 38S 
in figs. 11, 12 and 19) continue to function for a time as dorsal som- 
atic tributaries of the precardinal, and are not further involved in 
veno-lymphatic development. 
After the dorsal somatic branches (1S, 2S, and 3S) have separ- 
ated completely from the veno-lymphatic components (1VL, 
2VL, 3VL in figs. 12 and 19), the latter may or may not fuse with 
each other in the early veno-lymphatic stages. Usually, however, 
the veno-lymphatic components of tributaries land 2 (1VL, 2VL, 
in fig. 13), or of 2and 3 (2VL, 3VL,.in fig. 12) or of 1.2>angus 
(1VL, 2VL, 3VL, in fig. 20) unite with each other so that their 
individuality is lost and they then present a more sac-like ap- 
pearance than in the preceding stages. 
As a result of this fusion one or two of the originally separate 
veno-lymphatic components give up their primary connection 
with the precardinal vein (fig. 13 and 21). All of these variations 
are not shown in the diagrams but can easily be followed in the 
figures of the individual reconstructions. 
Typical instances of the separation of the dorsal tributaries 
into their veno-lymphatic and dorsal somatic components are 
afforded by series 138, (figs. 33-37), while the three primary divi- 
