78 PARTHENOGENESIS 



eggs which remain unfecundated, from which only drones are 

 developed, no spermatozoids will penetrate through the micro- 

 pyle, whilst the micropylar apparatus must exist in exactly the 

 same degree of development in all these eggs, as all eggs are 

 originally of one and the same kind and nature. 



Those eggs of Bees which have to undergo a fertilization are 

 fecundated at the moment when they slip past the orifice of the 

 seminal duct of the receptacle within the oviduct (vagina). At 

 this moment, as we may certainly suppose, some spermatozoa 

 are pressed forth out of the efferent duct of the seminal receptacle, 

 and these, in this way, by means of their mobility find an oppor- 

 tunity of penetrating through the micropylar apparatus into the 

 interior of the egg. That the act of fecundation of the insect- 

 egg actually takes place at the point in the vagina just men- 

 tioned, was asserted by me in the year 1837, and confirmed by 

 an observation which I made upon Musca vomitoria*. In 

 Musca vomitoria and its allies, which had not yet completed the 

 business of oviposition, or perhaps had been disturbed in it, and 

 had not immediately met with another suitable place for the 

 deposition of their eggs, the eggs occurring in the ovarian tubes 

 and in the oviduct differed in the following extremely interesting 

 manner. The egg, w r hich was fixed between the vulva and the 

 orifice of the seminal receptacle, had already begun to develope 

 itself, and contained an embryo; whilst the egg found in the 

 oviduct above the orifice of the seminal duct, which was per- 

 fectly equal in size with the preceding one, did not betray a 

 trace of the commencement of the development of the embryo, 

 any more than the eggs contained in the Fallopian tubes. In 

 such female Flies the seminal receptacle always contained mobile 

 spermatozoa. At that time w r e contented ourselves, in the ex- 

 planation of the process of fecundation, with the supposition that 

 the contact of the spermatozoids sufficed to incite the egg to 

 development ; more recently we have been compelled to drop 

 this theory of contact, since we have been able to trace the pene- 

 tration of the spermatozoids into the interior of the egg. The 

 process of impregnation will now 7 have to be more precisely con- 

 ceived in the following manner : The fecundation and capability 



* See Muller's Archiv, 1837, p. 424. 



