iv PKONEPHEOS 225 



the archinephric duct, which thus owes its origin to the fusion 



9l 



C 



Fig. 123. — Development of pronephros of Hypogeophis as seen in transverse sections. 

 (Alter Brauer, 1902.) 



A, embryo with 22 segments ; B, with 29 segments ; C, with 44 segments. A, dorsal aorta ; end, 

 endoderm ; gl, glomerulus ; Z.m, lateral mesoderm ; mc, myocoele ; my, myotome ; N, notochord ; no, 

 nephroeoele; ns, nephrostome; p.c, peritoneal canal; pn, pronepliric tubule; s.c, spinal cord,; sel, 

 sclerotome ; splc, splanchnocoele. 



together of the outer ends of the tubule rudiments belonging to 

 segments IV, V, and VI. 



VOL. II Q 



