RUDIMENTARY PRIMITIVE KIDNEYS. 



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which are, at first, very short, grow longer and broader, 

 each of the two primitive kidneys assumes the form of a 

 semi-pinnate leaf (Fig. 320). The urinary tubes (u) repre- 



b c b 



Fig. 319. — Rudimentary primitive kidney of embryonic Dog 1 . The pos- 

 terior portion of the body of the embryo is seen from the ventral side, 

 covered by the intestinal layer of the yelk-sac, which has been torn away, 

 and thrown back in front in order to show the primitive kidney ducts with 

 the primitive kidney tubes (a) : b, primitive vertebra) ; c, dorsal medulla ; 

 d, passage intd the pelvic intestinal cavity. (After Bischoff.) 



Fig. 320. — Primitive kidney of a human embryo : u, the urine-tubes of 

 the primitive kidney ; w, Wolffian duct ; w', upper end of the latter (Mor- 

 gagni's hydatid) ; m, Mullerian duct ; m', upper end of the latter (Fallopian 

 hydatid) ; g } hermaphrodite gland. (After Kobelt.) 



sent the tissue and the primitive kidney duct (iv) the 

 mid-rib. On the inner margin of the primitive kidney the 

 rudiment of the hermaphrodite sexual gland already 



