RUDIMENTARY PRIMITIVE KIDNEYS. 



409 



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

 each of the two primitive kidneys assumes the form of a 

 S3mi-pinnate leaf (Fig. 320). The urinary tubes (a) repre- 



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

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

 covered by the intestinal layer of the yelk-sac, wbich 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 vertebral ; c, dorsal medulla ; 

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



Pig. 320. — Primitive kidney of a human embryo : n, the urine-tubes of 

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

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

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



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

 mid-ril). On the inner margin of tlie primitive kidney the 

 rudiment of the hermaphrodite sexual gland already 



