TRANSLATOR'S PREFACE. 



OF all the discoveries which have been made of late years in 

 the history of the reproduction of animals, none is of greater im- 

 portance than that of the entrance of the spermatozoids into the 

 ovum, which is found to be the rule not only in the Animal, but 

 also in the Vegetable Kingdom. Nevertheless, but a few years 

 have elapsed since the final settlement of this disputed question, 

 and we have in the following observations of Professor Siebold 

 a clear proof of the occurrence of phaenomena, which, if they do 

 not invalidate the law, at least show that it is liable to some, 

 probably to many exceptions. 



Several years ago our author published some observations 

 upon a species of Psyche, which, as he stated, propagated without 

 copulation. He referred this singular occurrence to the same 

 class of phaenomena as the asexual reproduction of the Aphides, 

 the so-called Alternation of Generations ; and although it must 

 have been evident to every one who attentively studied his paper 

 that the circumstances of the two cases were widely different, it 

 was impossible, in the state of our knowledge at the time, to 

 propose any more satisfactory explanation of the phaenomenon. 

 Now, however, the whole face of affairs is changed. Von 

 Siebold, as will be seen in the following pages, has clearly 

 proved the existence of a sexual reproduction without fecunda- 

 tion, not only in the Psy chides, to which his former observations 

 related, but also in the Bees, in both as a regular occurrence, 

 and as an occasional phaenomenon also in the Silk-worm Moth ; 

 the latter circumstance giving a considerable degree of proba- 

 bility to some even of those supposed cases which our author dis- 

 cusses and rejects as inadmissible in the first section of his book. 

 For this phaenomenon of reproduction by virgin females the 

 author adopts the term Parthenogenesis, originally proposed by 



