228 METAMORPHOSES OF MAN 



generations of aphides possess female reproductive 

 organs — imperfect ones, it is true, but still quite 

 perceptible. In these organs, the essential part, the 

 ovary, appears to be constructed upon the same plan 

 as that of the viviparous individuals or scolices, and 

 that of the oviparous ones, which are the true females. 

 But in the latter we find genuine ova, with all their 

 characteristic parts ; whilst in the former we observe 

 only small granular masses, in which we can dis- 

 tinguish neither a true vitellus, nor a real germinal 

 vesicle, nor anything deserving the name of a germinal 

 spot.* 



In supposing that all animals reproduced by genea- 

 genesis are placed under the same conditions as those 

 which are presented by the Aphides, Professor Owen 

 has certainly gone beyond the results of direct obser- 

 vation ; even were it otherwise, we could not accept 

 his theory. 



In fact, Professor Owen, in explaining the pheno- 

 mena, refers to the origin of the simplest organisms, 

 and supports his views by Schwann's cell theory, a 

 doctrine whose errors, in many particulars, we have 

 already demonstrated. Certain beings, says the 

 English savant — for example, the monads, regarded 

 as the lowest infusoria, and the gregarinidae, which 

 are parasitic infusorians, living in the interior of other 

 animals — are constituted, really, of a single cell, 

 with its nucleus. Propagation is effected in them by 

 division of the nucleus, which produces that of the 

 entire animal.f Now, the ovum is formed essentially 



* When on the subject of true parthenogenesis, we shall deal 

 with these peculiarities. 



f From the circumstances that the nature of the nucleus of. 



