PLATE 5 
EXPLANATION OF FIGURE 
32 Reconstruction of the vascular channels and other structures in the region 
of the left pronephros in a 6-mm. embryo of Bufo vulgaris (K. E. C., series B 54), 
lateral view. X 166. 
1-4 v. seg., Ist to the 4th intersegmental veins; by the formation of interan- 
astomosis between them a plexus results, which may be called a venolymphatic 
one, in view of the fact that it subsequently gives rise to the lymph vessels in this 
region. 
cor. lym. ant., anlage of the anterior lymph heart. 
. Jug. int., vena jugularis interna. 
. Jug. ext., vena jugularis externa. 
. card. post., vena cardinalis posterior. 
. Cuv., duetus Cuvieri. 
d. 
proneph., pronephrie duct. 
nephst. I, II, et IIT, pronephrie nephrostomes. 
med. spin., medulla spinalis. 
I. II, III and IV, spinal ganglia; the 1st spinal ganglion is a very transitory 
and vestigial structure appearing for the first time in 6-mm. embryos and disap- 
pearing very soon after; the 2nd spinal ganglion becomes the Ist of the adult. 
vag., ganglionic prolongation of the vagus group (ef. fig. 31). 
124 
