THE URINOGENITAL SYSTEM 389 
Via. 225. — Sections of the embryonic metanephros of the chick 
to show developing tubules. (After Schreiner.) 
A. Nephric vesicle or primordium of secreting tubule (ur. t.) 
and collecting tubule (col. T.); 9 days and 4 hours. 
B. Elongation of nephrie vesicle; same embryo. 
C. Indication of renal corpuscle at the distal end of the 
forming tubule. 
D. The secreting tubule appears S-shaped. 
E. Secreting tubule well formed; 9 days and 21 hours. 
I’. Secreting tubule opening into collecting tubule; 11 days. 
