THE EMBRYOLOGY OF THE HONEY BEE 217 



by other investigators of the genital organs of insects. According 

 to this investigator the development of the male and female organs 

 of sex differ greatly. In the male the sex cells are derived origi- 

 nally from a cell produced by the fusion of the central product of 

 the division of the first polar body with the second polar body. 

 The cell thus produced gives rise by division to a considerable 

 number of cells which migrate in two groups to the dorsal side of 

 the embryo, where they again unite. From here they migrate 

 caudad, still increasing in number, to the abdominal region, where 

 they penetrate into the mesodermal tubes. Having arrived at this 

 point they become massed together to constitute the testes. The 

 ovaries, on the other hand, are formed from mesodermal cells, but 

 not from those of the mesodermal tubes, but from the loosely ar- 

 ranged cells derived from the mesoderm lying mesiad of the tubes. 

 An examination of Petrunkewitsch's figures (1903, Fig. 17) shows 

 that the mesoderm cells described as forming the ovaries are 

 identical with those which the present writer finds constituting the 

 epithelial envelope of the ovaries. The only remaining account of 

 the development of the genital organs of a hymenopterous insect, 

 aside from the more or less fragmentary accounts relating to the 

 parasitic forms, is in Carriere and Burger's description of the 

 development of the mason bee (1897). ^ n this form the rudi- 

 ments of the genital organs first become evident as thickenings 

 of the inner or visceral wall of the mesodermal "sacs" of the third, 

 fourth and fifth abdominal segments. Since the sex rudiments 

 thus belong to the wall of the mesodermal "sacs," they are 

 situated mesiad (or ventrad) of the mesodermal tubes. The rup- 

 ture of the visceral wall of the mesoderm takes place, as in the 

 honey bee, at the juncture of the mesodermal tubes with the re- 

 mainder of the inner wall, consequently the sex rudiments are 

 separated from the mesodermal tubes and subsequently come to 

 lie free within the secondary or definitive body cavity. The 

 epithelial envelope of the sex glands is formed by mesodermal 

 cells which lie laterad of the rudiments of these glands, and it 

 is by means of this envelope that they become attached to the 

 heart, as in the honey bee. Toward the close of development the 

 rudiments of the sex glands contract longitudinally so that at the 

 time of hatching they lie entirely within the limits of one segment, 





