DEVELOPMENT OF LYMPHATICS IN ANURA 73 
7 |v. jug.ext. sin. 
atin mee AOE be Maes B | lym. ae ie 
Fig. 8 Photomicrograph of a transverse section through the right ventral 
cephalic region in a 5-mm. embryo of Bufo vulgaris (Kampmeier Embryological 
Collection, series B 25, slide 1, section 71). X 690. (Zeiss Apochromat. Obj. 4 
and Compensat. Project. Oc. 4,). ep. epidermis; v. jug. ext. dex., vena jugularis 
externa dextra; lym., and initial lymphatic anlage of the primary maxillary 
sinus; the structure lying within the upper right-hand portion of the lumen of 
the vein is a yolk-filled blood cell. In this and the following photographs, the 
yolk globules can be easily distinguished from the dense cell nuclei by their 
smaller oval shape and their uniform gray color. 
Fig.9 Photomicrograph of transverse sections through the left ventral 
Cephalic region in a 6-mm. embryo of Bufo vulgaris (K. E. C., series B 54, slide 1, 
Sections 75 (A) and 80 (B). X 690. v. jug. ext. sin., vena jugularis externa sin- 
istra; lym., initial anlagen of the primary maxillary sinus. 
