220 BEES AND BEE-KEEPING. 



remained entirely constructive in character, until I was 

 fortunate enough to establish for it an anatomical 

 basis,* which not only explains the facts, but the 

 structures which make them possible. 



Parthenogenesis, or reproduction without fecunda- 

 tion, by virgin and perfect females provided with 

 ovaries and spermatheca, is no new fact in entomology. 

 It received recognition at first in the earlier half of 

 the eighteenth century, in the case of some virgin 

 female silk moths, and afterwards in others of the 

 Bombycidse, all of which produced eggs hatching out 

 both sexes. Later, an incomplete parthenogenesis was 

 observed in the Psychidas and some nearer relatives 

 of the bee (the gall flies), the virgin females laying 

 eggs yielding exclusively females (the less perfect 

 form in these genera) ; the process being repeated, 

 during twenty generations, without a single male in- 

 dividual presenting itself, or one case of impregna- 

 tion having occurred. Indeed, amongst some moths, 

 the male is at present altogether unknown. Nor have 

 we at all exhausted our knowledge of these surprising 

 variations from a rule formerly thought to permit of 

 no exception ; for, amongst other similar cases, in a 

 species of Cecidomyia, a small insect, living, in the 

 larval state, beneath the bark of trees, the larva is 

 itself fertile, producing creatures in its own likeness, 

 which at maturity tear open the side of the parent 

 and escape, themselves to similarly give rise to another 



* " The Apparatus for Differentiating the Sexes in Bees and Wasps. 

 An Anatomical Investigation into the Structure of the Receptaculum 

 Seminis and Adjacent Parts." F. R. Cheshire. Journal Royal Micro- 

 scopical Society, February, 1885. 



