PAETHENOGENESIS. 29 



The Aphides, or plant-lice, which are so commonly found 

 parasitic upon plants, are seen towards the close of autumn 

 to consist of male and female individuals. By the sexual 

 union of these true ova are produced, which remain dormant 

 through the winter. At the approach of spring these ova are 

 hatched ; but, instead of giving birth to a number of males 

 and females, all the young are of one kind, variously regarded 

 as neuters, virgin females, or hermaphrodites. Whatever their 

 true nature may be, these individuals produce viviparously 

 a brood of young which resemble themselves ; and this second 

 generation, in like manner, produces a third, and so the pro- 

 cess may be repeated, for as many as ten or more generations, 

 throughout the summer. When the autumn comes on, how- 

 ever, the viviparous Aphides produce in exactly the same 

 manner a final brood ; but this, instead of being composed 

 entirely of similar individuals, is made up of males and females. 

 Sexual union now takes place, and ova are produced and 

 fecundated in the ordinary manner. 



The bodies from which the young of the viviparous Aphides 

 are produced are variously regarded as internal buds, as 

 * pseudova ' (i.e. as bodies intermediate between buds and 

 ova), and as true ova. 



Without entering into details, it is obvious that there is 

 only one explanation of these phenomena, which will justify 

 us in regarding the case of the viviparous Aphides as one of 

 true parthenogenesis, as above defined. If, namely, the 

 spring broods are true females, and the bodies which they 

 produce in their interior are true ova, then the case is one of 

 genuine parthenogenesis, for there are certainly no males. 

 The case might still be called one of parthenogenesis, even 

 though the bodies from which these broods are produced be 

 regarded as internal buds, or as 'pseudova; ' for a true ovum 

 is essentially a bud. If, however, Balbiani be right, and the 

 viviparous Aphides are really hermaphrodite, then, of course, 

 the phenomena are of a much less abnormal character. 



In the second case of alleged parthenogenesis which we 

 are about to examine, namely, in the honey-bee, the phenomena 

 which have been described cannot be said to be wholly free 

 from doubt. A hive of bees consists of three classes of indivi- 

 duals 1. A ' queen,' or fertile female ; 2. The ' workers,' which 

 form the bulk of the community, and are really undeveloped 

 or sterile females ; and 3. The ' drones,' or males, which are 

 only produced at certain times of the year. We have here 

 three distinct sets of beings, all of which proceed from a 

 single fertile individual, and the question arises, in what 

 manner are the differences between these produced ? At a 



