The Developmeut of the Hymen 91 



tions. By the beginning of the nineteenth week the hymen is visible as 

 a fold rising from the posterior wall of the vagina directly above the 

 point of entrance of the vagina into the sinus urogenitalis. To meet 

 this a shorter fold from the anterior wall grows downward. The two 

 folds unite, leaving a semi-hmar opening. The growth of the hymen 

 is very rapid. He continues : 



"Der Umstand dass die Hymenalmembran in der Nahe der Stelle 

 entsteht an welcher sich die Allantois imd Mueller'schen Gange in der 

 Cloake begegnen, und der Sinus Urogenitalis abscheidet, hat wieder- 

 holt zu der Yermuthung geflihrt, dass der Hymen mit einem Ent- 

 wickelungsgebilde der frliheren Zeit in Zusammenhang stiinde. Je 

 genauer man aber die frliheren Entwickelungsstufen in ihrer Weiter- 

 bildung verfolgt, desto mehr wird man iiberzeugt, dass ein soleher 

 Zusammenhang nicht vorliegt. Wir haben beim menschlichen Embryo 

 einen langen Zeitraum, den Abschnitt von der 9-17ten Woche, in 

 welchem wir den Mittelstufen zwischen Hymen und den an seiner Ent- 

 wickelungsstelle friiher zusammengetrolfenen Gebilden nachspiiren 

 konnen. Das Eesultat ist negativ. Der Hymen ist ledigiich eine 

 spiitere Bildung, welche sich nicht in continuirlicher Fortenwickelung 

 an friihere Formen anschliesst." 



Gellhorn (•'04) also holds to the vaginal theor}^, although I believe ho 

 does not sufficiently emphasize in his article the difference betAveen his 

 conception and the above-mentioned vulvo-vaginal theory. Budin de- 

 scribes the vaginal bulbus as projecting into the urogenital sinus. Into 

 this protruding conus, according to Gellhorn, the vaginal connective tissue 

 grows, so that, with the possible exception of a thin layer of epithelium 

 of the urogenital sinus on the outside, the entire hymen is of vaginal 

 origin. 



While it is thus seen that there is no lack of theories, their foundation 

 is for the greater part the most meagre and inconclusive evidence. Only 

 one man so far as I know studied serial sections of the hymen micro- 

 scopically, and that one — Klein ('94)- — studied but a single case in this 

 way.^ INTo one has thus far made use of serial sections in a number of 

 embryos of various stages of development for an investigation of the 



'I do not include in this consideration the two embryos tliat Klein cut in 

 ti'ansverse serial section, hnt only the one sectioned sagittally. Transverse 

 sections, imless some sort of reconstruction is made (and this was not done), 

 are not favorable for a study of the hymen in its relations to neighboring 

 structures, a point which Klein himself concedes. 



