Till- nllCANs id Illl. MIM'I i 



371 



of its own c.-lls. and givefl ri-e to a -olid ci.nl. uhich lies direct Iv 

 betw.en the IHCM .iiephric d net and the peritoneal ej.ii h limn, which 

 is here somewhat thickened. Tlie funnel product d by the invagina- 

 tion now becomes the oetium abdominale tube, but tin- .-olid cord of 



cells, which is soon hollow, d out and finally opens behind into the 

 eleaca. b cuines t he 

 Miillerian duct. 



It' the repreM-nta- 

 tion just given is t -or- 

 n ct in all particulars, 

 the Miillerian ducts 

 in the Anamnia and 

 the Amniota, al- 

 though possessing 

 the same location, 

 form, and function, 

 would still be non- 

 homologous organs, 

 because their develop- 

 ment is dim-rent. 

 For the one is split 

 off from the meso- 

 nephric duct, the 

 other is formed in- 

 dependently by a 



new invaginatioil of Fig. 210. Cross section through the mesonephros, the funda- 

 tli,. PrVpli'iir ment of the Miillerian duct, and the sexual gland of a 



Chick of the fourth day. | ru. Ma-nitied ir,u 



Such a surprising diameter*. 



If arroo +r m, Mesentery ; Z, somatojilru: the jjenuiiuil 



..nitlifliuin fn.iu which th,- Miillt-rhin duct(:> lias been 



invaginated ; . tlii. k--m-"l ]>.ut ..f tht- j:i-nnin:il c]iithi'liuin. 

 in which tlie primm v st-xniil o-ll-i, r'ainl , lii- ; E, modi- 

 tied nieat-ncliynie out of which the .-tr<'in;i of the sexual 

 gland is formc<l ; }\'K, UR-MUH | "iiephric duct 



us, however, upon 

 grounds of compara- 

 tive anatomy, to be 

 very improbable, and 



therefore the attempt made by some inv -Migators to reft r back 

 the conditions found in the Amniota to such afl exi^t in the 

 Ai.amnia deserves every attention. This would be possible if 

 the statements of BALFOUR AND Srn.\\nK. which have however 

 been called in question by others (JANOSIK), should be confirmed. 

 A> we have previously seen, there are two different regions to 

 bi i distinguished on the Miillerian duct an anterior, which is 

 the degenerated pronephro- and bean the orifice of the tuba. 



