VII PARTHENOGENESIS 243 



bee-keepers, and such naturalists of the limited, or 

 " gardener " type, had asserted reproduction by means 

 of unfertilised eggs to take place. It must be re- 

 membered that he was himself a strong opponent 

 in 1850 of the supposition which he has now shown to 

 be justified in fact, and that Leuckart in his article 

 " Zeugniss," in Wagner's Handworterbuch, and in 

 other publications, preceded him as an advocate for 

 the existence of true parthenogenesis, endeavouring, 

 by microscopical researches, to give a solid observa- 

 tional basis to Dzierzon's hypothesis. It was not 

 until 1857 that Siebold published his observations 

 on bees, demonstrating what had been previously 

 supposed, viz. that the queen-bee exhausts her store 

 of received sperm in fertilising eggs which give rise to 

 females only, and that then she lays unfertilised eggs, 

 which become drones only, whilst the unfertilised 

 worker-females also lay eggs which give rise to drones : 

 and again that in certain moths (Psyche and Solenobia) 

 unfertilised ova develop and produce females only. 

 Leuckart followed (1858) with his Zur Kenntniss des 

 Generations-ivechsels und der Parthenogenesis bei den 

 Insekten. In this work, whilst asserting his claims to 

 the merit of first espousing the cause of true par- 

 thenogenesis, Leuckart gives an excellent view of the 

 general signification of the phenomena, and insists on 

 the importance of extended histological observation 

 in the examination of alleged cases of parthenogenesis. 

 In his present work Siebold cannot be charged with in 

 any way neglecting this part of his subject, for he has 

 given most important and minute descriptions of the 



