DEVELOPMENT OF LYMPHATICS IN ANURA 95 
One detail still remains to be considered in the morphogenesis of 
the anterior lymph heart, namely, the shifting of the efferent portal, 
or ostium venosum. In the earlier stages, this connection is with 
Cu eo ee NR se) Ss 
lym. com. jwg.et lat. 
my | 
et 
X 
XK 
ines 
Fig. 19 Photomicrograph of a transverse section through the left anterior 
lymph heart region in an 8-mm. embryo of Bufo vulgaris (K. E. C., series B 49, 
slide 2, section 112). X 340. v. vert. ant., vena vertebralis anterior, branch of 
the pronephric sinus (si. proneph.), its mouth being that of the original third 
intersegmental vein; *, point of former connection, in the form of a small spur, 
between the common segment of the jugular and lateral lymphatics and the 
lymph heart; gan. I//, third spinal ganglion. Other references as before. 
the pronephric venous sinus and is found squarely on the ventral 
side of the heart (fig. 32). This condition is changed by three 
factors: first, the breaking away of the posterior channel of the 
into that of the fully formed animal represents another section of the original 
monograph and will appear later as a separate paper. 
