50 



THE CLASS OF INSECTS. 



pseudova, must depend upon a something impressed upon the 

 constitution of the parent before it was brought forth by its 

 viviparous progenetrix." (Huxley.) 



Siebold has also shown that the "ova of the Queen-bee pro- 

 duces females or males, according as they are fecundated or 

 not. The fecundated ovum produces a queen or a neuter 

 according to the food of the larva and the other conditions to 

 which it is subjected ; the unfecundated ovum produces a 

 drone." This is analogous to the agamic reproduction of 

 Aphis, and "demonstrates still more clearly the impossi- 

 bility of drawing any absolute line of demarcation histologi- 

 cally between ova and buds." 



This process of reproduction is not known in the Myriapods. 

 It occurs among the mites (Acarina), and occurs in isolated 

 genera of Hemiptera (Aphis, Chermes, Lecanium, and Aspidi- 

 otus according to Gerstaecker). 



Among Lepidoptera the Silk-moth sometimes lays fertile 

 eggs without previous sexual union. This very rarely hap- 

 pens, for M. Jourdain found that, out of about 58,000 eggs 

 laid by unimpregnated silk-moths, many passed through their 

 early embryonic stages, showing that they were capable of 

 self-development, but only twenty-nine out of the whole 

 number produced caterpillars. (Darwin.) Several other moths * 

 have been found to lay fertile eggs without previous sexual 

 union, and among Hymenoptera, Nematus ventricosus, Cynips, 

 Neuroterus, perhaps Apophyllus (according to Gerstaecker), 

 and Cynips spongifica (according to Walsh, Proceedings of 



*We give a list from Gerstaecker (Bronn's Classen und Ordnungen des Thier- 

 reichs) of all the known cases of agamic reproduction in this suborder, with the 

 number of times the phenomenon has been observed, and the names of the ob- 

 servers. 



Gastropacha quercus, once (Plieninger). 



Liparis dispar, once (Carlier). 



" Eager moth" (? Liparis dispar), (Tardy, 



Westwood). 



Liparis ochropoda, once (Popoff). 

 Orgyia pudibiinda, once (Werneburg). 

 Psyche apiformis, once (Rossi). 



" helix (Siebold). 

 Solenobia lichenella (Siebold). 



" triquetrella (Siebold). 

 Bombyx mori, several times. 



Sphinx ligustri, once (Treviranus). 

 Smerinthus populi, four times (Nord- 



mann). 



Smerinthus ocellatus, once (Johnston). 

 Euprepia caja, five times (Brown, etc.). 



" mllica, once (Stowell). 

 Telea Polyphemus, twice (Curtis). 

 Gastropacha pint, three times (Scopoli, 



etc). 



Gastropacha quercifolia, once (Basler). 

 potatoria, once (Burmeis- 

 ter). 



The subject has been also discussed by Siebold in his work entitled, A true Par- 

 thenogenesis in Lepidoptera and Bees; by Owen, in his "Parthenogenesis," and 

 by Sir J. Lubbock in the Philosophical Transactions, London, vol. 147, pt. 1. 



