268 PARTHENOGENESIS VII 



rabbit, thoroughly separated pathologically from the 

 uterus, Professor v. Hensen of Kiel found ova in various 

 stages of yelk-division, and some of their cells had 

 even advanced into a branched condition. Dr. 

 Oellacher of Innsbruck has observed stages of yelk- 

 division in unfertilised hen's eg;as. In fishes, in 

 1859, Agassiz observed yelk-division occurring in the 

 eggs of Gadidse, whilst yet in the ovary, and con- 

 sidered it to be due to impregnation, even stating 

 that he had seen certain fishes place themselves in 

 such a position as to favour this supposed intra- 

 ovarian fertilisation. Burnett has since investis'ated 

 the case, and concludes that the yelk -division is 

 independent of fertilisation, a supposition which is 

 rendered in every way probable from other researches 

 on the fish egg ; but, curiously enough. Dr. Burnett 

 thinks these eggs should be regarded as "germs," and 

 not as " true eggs," an opinion to which Siebold, of 

 course, is completely opposed, and one which, in in- 

 vertebrate cases, has been shown to be untenable. 



Siebold does not allude to those cases of ovarian 

 cysts found occasionally in the unfertilised human 

 female, and containing hair and teeth — a phenomenon 

 which we should be glad to see further discussed and 

 investigated, since, as far as we can remember, the 

 origin of the contents of such cysts from irregularly 

 developing ova is probable. The eel is suggested as 

 a possible parthenogenetic vertebrate. It is a very 

 strange fact that we are still ignorant of the ripe eggs 

 and embryos as well as of the males of the eel, even 

 as in the time of Aristotle. With the foUowinof words 



