12 



ELUCIDATION OF THE CASES HITHERTO DESCRIBED AS 

 PARTHENOGENESIS. 



SINCE the remarkable reproductive history of the Aphides 

 must be transferred into the domain of the Alternation of Gene- 

 rations, it becomes a question whether we are not acquainted 

 with other facts in the history of Insects, which are to be re- 

 garded as Lucina sine concubitu or Parthenogenesis. In point of 

 fact, observations have been published by the most different 

 Entomologists of old and modern times, which should lead us to 

 infer the pretty widely diffused existence of a true Partheno- 

 genesis amongst Insects. But all these narratives of female 

 Bombyces and other moths, which, when kept isolated and with- 

 out any copulation, laid eggs from which young were afterwards 

 excluded, require a more exact investigation; for before we 

 allow an important physiological law, derived from multifarious 

 observations, to be thrown down by such statements, it is ne- 

 cessary to determine, whether we can put implicit faith in 

 these narratives, whether we have to do here with credible facts, 

 or whether, in this case, a fact has not been rather concluded 

 from superficial, unsatisfactory and scanty observations, than 

 positively proved. I have already indicated these cases*, as 

 being such as to require an exact investigation, to get rid of every 

 doubt as to the assertion that a spontaneous evolution of brood 

 can really take place in the eggs laid by virgin female insects. 

 I had at that time proposed to myself to submit the cases brought 

 forward by so many naturalists and narrated again and again, by 

 which the existence of a Lucina sine concubitu was to be proved, 

 to a careful criticism. This criticism I will now undertake, in 

 order to show how little of all these assertions remains admis- 

 sible ; for as we have to do with the maintenance or abolition of 

 a physiological theoretical law, the importance of which has long 

 been recognized, it follows as a matter of course, that none but 



* See Zeitschrift fur wissenschaftliche Zoologie, 1849, p. 97. 



