371 



is apparently of no great (if any) functional importance in the nutri- 

 tion of the embryo. 



Parturition. 



As in P e r a m e 1 e s so in D a s y u r u s there is at parturition 

 not only no loss of maternal tissue but the foetal membranes in 

 greater part remain in the uterus and are gradually absorbed in situ 

 through the agency of maternal leucocytes. Like the allantoic pla- 

 centa of P e r a m e 1 e s , the yolk-sac placenta of D a s y u r u s is of 

 the contra-deciduate type. 



As regards the mode of birth of the young, the unexpected and 

 interesting discovery was made that exactly as in Perameles^), 

 they reach the exterior through a direct median passage constituted 

 in front by the median vaginal and behind by a cleft-like rupture 

 (the pseudo-vaginal passage) in the connective tissue forming the 

 direct continuation of the median vaginal. The pseudo-vaginal passage 

 is here also a mere temporary split in the connective tissue, its 

 formation is accompanied by extravasation of blood and it never is 

 at any period of its existence provided with an epithelial lining. In 

 Dasyurus, the passage is much shorter than in Perameles owing 

 to the considerably greater length of the urogenital sinus in the 

 former animal. 



Serial sections of the urogenital organs of a female Dasyurus 

 which was killed after one only of the young had been born show 

 the actual rupture in the epithelium lining the urogenital passage, 

 through which entrance had been gained to the latter. This opening 

 has the form of a longitudinal narrow cleft with ragged lips, pro- 

 jecting from which are fragments of the foetal membranes together 

 with leucocytes and maternal blood clots. 



After parturition is completed, obliteration of the pseudo-vaginal 

 passage proceeds with remarkable rapidity. On the second day fol- 

 lowing, the epithelial rupture is completely healed, and on the third 

 day, the passage itself is no longer patent. Its previous position 

 indeed is hardly now recognisable: so much so that no one, un- 

 acquainted with the facts, would remark from the sections that a 

 passage had ever been in existence. Such being the case it is evi- 



1) Hill, Contributions to the Morphology and Development of the 

 Female Urogenital Organs in the Marsupialia. I. On the Female Uro- 

 genital Organs of Perameles, with an Account of the Phenomena of 

 Parturition. Proc. Linn. Soc. N. S. W., 1899, Part 1, March 29. 



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