204 



UKOGENITAL SYSTEM 



which was, however, put forward before the appearance of Keibel's paper on Echidna, is 

 that the urogenital sinus represents the cloaca, and the formation of the upper septum is the 



FIG. 256. SECTION THBOUGH AN EMBRYO OF TALPA EUBOP^A. (After^Soulie.) 



zw, bud from coelomic epithelium, the rudiment of suprarenal body (cortical portion) ; v.c.p., posterior 

 cardinal vein ; glm, glomerulus ; w.d., Wolffian duct ; v, vein. 





!il# J 



: jll 



&% : #^ " 



mtt 



FIG. 257. SECTION THROUGH A CHBOMAFFIN-BODY IN A 44 MM. HUMAN EMBRYO, TO SHOW THE 

 DIFFERENTIATION OF THE PRIMITIVE INDIFFERENT SYMPATHETIC CELLS. (Kohn.) 



p, p, mother chromaffin-cells (Phiiochromoblasts) ; sy, sympathetic cells; b, blood-vessel. 



expression of the closure of the mouth of the hind-gut into that chamber, the rectum proper being 

 a sub-caudal extension of the terminal part of the gut, which becomes secondarily connected 

 with an ectodermic anal invagination. 



