PREFACE. 



ENGAGED in constant efforts to trace and clear up the history 

 of animal reproduction, as far as this is permitted to human 

 discernment, I have been guided to a phenomenon in Insect- 

 life which had for a long time remained obscure to me, I refer 

 to the power of reproduction of some female Insects which 

 remain unfecundated, as this not only appeared to be a great 

 mystery, but even a fact never yet firmly established, and 

 therefore still doubtful. I always found this so-called Lucina 

 sine concubitu treated by physiologists as a sort of curiosity ; 

 the same examples from Insect-life, derived from the older ob- 

 servers, were constantly referred to as vouchers. The question, 

 whether the fact referred to was supported upon a firm basis, 

 remained at the same time altogether unnoticed. As every kind 

 of statement with regard to Lucina sine concubitu was received 

 with so little caution and without suspicion, new observations 

 were added to the older defective notices of this kind ; but these, 

 in the same way, appeared inadmissible as soon as they were 

 carefully analysed. 



Since the process of the fecundation of the egg has become 

 much better understood by the recent discoveries of Newport, 

 Keber, Bischoff, Leuckart, Meissner, and Bruch, one was com- 

 pelled to say, that all the cases of Lucina sine concubitu observed 

 in former or modern days might be founded upon delusion 

 or error, because up to this time the knowledge of the con- 

 ditions under which fecundation takes place was still extremely 

 imperfect. Now, when the physiology of reproduction has 

 been enriched with many exceedingly important discoveries, 

 and by these some essential points in the act of fecundation, 



