PLATE 2 
EXPLANATION OF FIGURE 
29 Reconstruction of the vascular channels of the ventral cephalic region in 
a 6-mm. embryo of Bufo vulgaris (IK. E. C., series B 53), ventrai veiw. X 125. 
v. jug. ext., vena jugularis externa. 
a. car. ext., arteria carotis externa. 
g. thyr., glandula thyroidea. 
ao., aortic arches. 
vent., ventriculus of the heart. 
d. Cuv., ductus Cuvieri. 
sin. ven., Sinus venosus; its cut edge shows its attachment to the liver, for at 
this period the hepatic sinusoids open directly into it. 
The lymphatics, the anlagen of the sinus maxillaris primigenius arise inde- 
pendently of each other along the venous components of the jugulocarotid 
plexus; some of them have severed contact with the blood vessel wall, while 
others still adhere to it. 
