.PHYSIOLOGY OF THE INVERTEBRA7A. 437 



parthenogenetic or viviparous female is different from the 

 oviparous form; for in the former the spermathecse and 

 colleterial glands are entirely absent, whereas these organs 

 are present in the latter.* 



" The unimpregnated, apterous, caterpillar-like females 

 of the Lepidopterous genera Psyche and Solenohia, lay eggs 

 out of which only females issue. The males occur but rarely 

 and locally, and, from the impregnated eggs, males and females 

 issue in about equal numbers." Among ants, wasps, and 

 humble-bees, the ovaries of the neuters often contain ova ; 

 and in the two last-mentioned insects these ova give rise to 

 young (sex ?). 



In Polistes gallica the so-called neuters (9) lay ova, 

 which develop only male insects ; and the unimpregnated 

 females of Nemahts vcntricosus lay ova which give rise to 

 males. f 



Parthenogenesis among hive-bees is an established fact; 

 the young unwedded queen-bee lays ova profusely, but all of 

 them give rise to males or drones. The impregnated ova, 

 however, give rise to females, which become either queens or 

 neuters, according to the supply of food given to them. If a 

 queen-bee dies, the inmates of the hive feed a selected 

 female larva on " chyle-food," elaborated in the so-called 

 chyle-stomach of the nurses, until it assumes the pupal change, 

 from which it emerges a perfect female. The future worker 

 or neuter is weaned on the fourth day, and fed henceforth on 

 honey and digested pollen, with the result that its ovaries 

 are rudimentary and sterile, while its further genital struc- 

 ture renders it incapable of mating. The fecundation of the 

 queen-bee takes place within a few days of her quitting the 

 cell, and lasts for life ; the millions of spermatozoa dis- 



* See Prof. Huxley's paper in Transactions of the Linnean Society, 1857 ; 

 Balbiani's paper in Annates des Sciences Natv/relles, 1869-72; and Von 

 Siebold's Anatomy oftlie InveHebrata. 



t Parthenogenetic females which produce male young are termed arren- 

 tokous, while those which produce female young are termed thelytokous. 



