Effects of Castration ni Insects 427 



zoa entering the same egg, one only fusing with the egg nucleus 

 and the other not uniting, but developing without combining with 

 any parts of the egg nucleus." These hypotheses have no very 

 cogent facts to support them and I fail to see how they have any 

 advantage over the hypothesis which was advanced by Donhof 

 as long ago as i860, to the effect that the gynandromorph arises 

 from the fusion of two eggs, only one of which, in the case of 

 the honey' bee, is fertilized. In its original form Donhof's hypothe- 

 sis is incomplete, but I believe that its plausibility is increased by 

 addition of the following considerations. We may assume with 

 Beard ('02), von Lenhossek ('03), Renter ('07), Morgan ('09) 

 and others that the gonochoristic Metazoa produce two kinds of 

 eggs, male and female, which may or may not differ in size but 

 differ in sex even as oocytes. Now we know from zur Strassen's 

 researches on Ascaris ('98) that two eggs may fuse and neverthe- 

 less give rise to a single embryo of perfectly normal structure 

 though of twice the normal size. In Ascaris the fusion occurs 

 after the oocytes have reached their full growth, but a fusion of 

 younger oocytes would be, in all probability, not only more readilv 

 accomplished but lead to the formation of a single embryo of the 

 normal size. The structure of the ovarioles of insects indicates 

 that it would be a very easy matter for two young oocytes to be- 

 come enclosed in the same follicle, too easy, indeed, to accord, at 

 first glance, with the fact that gynandromorphs are such rare 

 anomalies. But if two female or two male oocytes fused no gy- 

 nan dromorph would result, and the chances of either of these fu- 

 sions of like oocytes occurring would be quite as great as that of 

 two oocytes of opposite sex. If this be the way in which gynandro- 

 morphs arise, we should have to explain the occurrenceof thelateral 

 type of the anomaly by supposing that the plane of fusion of the 

 two eggs be omes the median sagittal plane of the future insect, 

 whereas in the frontal type this plane would be transverse to the 

 longitudinal axis. Finally, in the mixed and decussating types 

 we should have to suppose that the male and female egg-mate- 

 rials are mixed or interpenetrate one another toa variable degree. 

 The hypothesis here sketched has the advantage of permitting of 

 some slight cytological verification, for microscopic examination 



