26 PARTHENOGENESIS IN SOME 



at first sticking loosely into the posterior free opening of the 

 sac, which was firmly spun clown, but also frequently fell down, 

 so that the female Solenobice always lay their eggs immediately 

 in the sac itself. The females of the sac-bearing genus Talce- 

 poria, which approaches most closely to Solenobia, proceed in 

 exactly the same way in escaping and laying their eggs. 



But what particularly struck me in the behaviour of the female 

 Solenobice, was the circumstance that they commence the busi- 

 ness of oviposition very soon after their exclusion, whilst the 

 females of Fumea put off their egg-laying until they have copu- 

 lated, by which means many of the latter in my breeding-cages, 

 in which there was sometimes a deficiency of males, died of 

 vain expectation in their virgin state, without having previously 

 discharged their eggs. The female Solenobice, on the contrary, 

 possessed such a violent impulse to lay their eggs, that when I 

 removed them from their sacs, they pushed their laying-tube 

 about in search of the orifice of the sac, and at last let their 

 eggs fall openly. If I had wondered at the zeal for oviposition 

 in these husbandless Solenobice, how was I astonished when all 

 the eggs of these females, of whose virgin state I was most 

 positively convinced, gave birth to young caterpillars*, which 

 looked about with the greatest assiduity in search of materials 

 for the manufacture of little sacs ! 



After I had been first surprised by this phenomenon in the 

 spring of the year 1850, I could not but be convinced that De 

 Geer, Scriba, and Speyer, who reported that these animals laid 

 fertile eggs without previous copulation, had not deceived them- 

 selves, as I previously supposed f; nevertheless, I could not 

 persuade myself that this phenomenon was to be explained as 

 Parthenogenesis, but rather thought I recognized in the whole 

 phenomenon, an asexual propagation analogous to the repro- 

 duction of the Aphides, regarding the female Solenobice which 

 had laid eggs capable of development without copulation as 

 asexual nurses. In this way I quieted myself with the idea that 

 an alternation of generations occurred in the insect-world, not 



* This production of fertile eggs without previous copulation has also been 

 observed in Solenobia lichenella by Wocke {op. cit. supra, p. 182) and Reutti 

 (see Beitrage zur rheinischen Naturgeschichte, Heft 3, 1853, p. 1/6). 



t See my memoir above referred to, on the Reproduction of Psyche, p. 99. 



