KEPKODUCTION OL' APHIDES. Ill 



animals the males do not exist. Von Siebold even 

 surmised that in certain species a process of elimina- 

 tion was in action as regards the males, and that such 

 a process finally would result in a strict partheno- 

 genetic reproduction of such species. 



But it will be very unsafe to dogmatize on negative 

 evidence as to the non-existence of males. The male 

 of the Bntomostracan Apus was long unknown, but 

 in 1858 it was discovered by Kozubouski. Still, this 

 sex occurs so very infrequently, that not one could be 

 found amongst the 5790 individuals said to have been 

 examined by Siebold. Again, Sir John Lubbock 

 examined 193 specimens of Apus cancriformis taken 

 from a pond near Krakow; and amongst these he 

 discovered but one single male. The fact seems to 

 become more and more patent, that as we become 

 better acquainted with the metamorphoses of the 

 lower animals, and the very different larval aspect 

 they can assume, such anomalies will disappear. 

 Under the present conditions of life a conjuncture 

 of male and female cells seems to be all but imperative 

 for the renewal of life-cycles. 



The absence of a spermatheca in some low aquatic 

 forms might argue the non-existence of males; but here 

 possibly a large volume of the male element, diffusing 

 itself through the surrounding water, may ensure 

 action on the ova, in a manner similar to the milting 

 of fish, and make this sperm receptacle unnecessary. 



In 1856 Yon Siebold gave a rude shock to the 

 prevailing current opinion ; founded on Harvey's 

 dictum " ornne vivum ex ovo," * by showing that a 

 true parthenogenesis obtaius amongst moths and bees. 

 Before his time it had been almost uniformly assumed 

 that without the action of the spermatozoon on the 

 ovum no fertilisation could occur. 



In 1857 the same biologist demonstrated that the 

 queen bee exhausts her store of sperm in fertilising 



* This aphorism, usually attributed to Harvey, appears to be a 

 contraction of bis words, already quoted. 



