DEVELOPMEST OF THE EiETrs. 



Ill 



development of the genital organs, while another gives rise to organs 

 whose use is not exactly known — such as the Rosennuiller organ, whicii 

 is very developed in the Equine fcutus, and the canals of Gaertner visible 

 in the Cow. 



With regard to the uhinaky oiuiANH, we have mentioned how the 

 allantois was derived from the terminal portion of the intestine ; it only 

 now remains to add that the uriiuin/ bladder is derived from the 

 abdominal portion of the allantois, which is merely a dilatation of that 

 sac. During fcetal life the bladder is extended, by the urachus, to the 

 umbilical ring ; but after birth this canal is obliterated, and the bladder 

 retires to the bottom of the pelvic cavity. 



The kidjicys appear a long time after the Wolrtian bodies. They 



Fig. 5 



Male F(KTIs ok the Makk at Fivk and a Hai.k Munth.s : the Ahdomen 

 opened and te.st1cle.s expo.skh. 



l,Thii;li8 ; 2, I'eniH— neither Scrotum nor Prepuce an; y«;t fonnwi ; 'i. IJIa/ifler, 

 with the two Umbilical ArterieH ; 1, Abdominal Parietes ; '>, Douglas' Fora- 

 men, with the two Afferent CanalM, h, //; 6, KidneyH ; 7, .Supra-renal Cap 

 Hule8 ; 8, Rectum ; 9, MeHorchJH or Spermatic Cord ; a, fTubernaculuni 

 Hunterii ; a', Internal Inguinal King ; b, b, Efferent Ductn ; <:, c, To*ticlejj ; 

 d, d, Pampinifurm Plexus. 



show themselves in the form of two culs-dc-sac, constituted by tlie 

 upper wall of the small vesicle of the allantois. These small cavities 

 become ramified, and are ultimately replaced by solid tubercles, in 

 whose interior are developed the tubuli uriniferi and the Malpighian 

 tufts. According to some observers, the kidneys only subsequently 

 communicate with the ureters, which are developed separately in the 

 middle lamina of the blastoderm, and terminate in the pelvic portion 

 of the allantois. 



The genital organs of the male a,nd female offer, at the commencement 

 of their development, the greatest analogies. For a certain time it is 

 impossible to distinguish the sexes ; so that some authorities propose 

 to term this the " indifferent " state of the genital organs. Afterwards 



