THE URIXOGENITAL SYSTEM 



381 



this process extends over the whole of the latter period of incu- 

 bation, and is completed at hatching. Parts, however, remain 

 in the male in connection with the testis; non-functional remnants 



Mn.T: 



n.T. 



FIG. 219. Profile reconstruction of part of the 



mesonephros and diverticulum of the ureter of 



a duck embryo of 50 somites. (After Schreiner.) 



Cl., Cloaca. Int., Intestine. Mn. T., Meso- 



nephric tubules, n. T., Nephrogenous tissue. 



Ur., Ureter. W. D.. Wolffian duct. 



XXXII, XXXIII, XXXIV, Somites of the 

 same number. 



may also be detected in the female (p. 401). It is difficult to 

 state the exact period of beginning and cessation of function of 

 the mesonephric tubules. Judging from the histological appear- 



FIG. 218. Profile reconstruction of part of the Wolffian duct and primordia 

 of mesonephric tubules (represented by circles) of a duck embryo of 45 

 somites. (After Schreiner.) 

 XXIV, XXV, etc., position of the corresponding somites. Lines 114 A, 



114 B, 114 C, represent the positions of the sections shown in these figures. 



