142 THE MENDEL JOURNAL 



femaleness, to effect fertilisation. It therefore fol- 

 lows as a natural sequence that from fertilised eggs 

 only females are produced. 



These being the facts then with regard to insects, 

 phylloxerans, and aphids, and, further, it being 

 known as an observed fact that in the bee one half 

 of the spermatozoa undergo degeneration, we may be 

 justified in believing that the same explanation is 

 applicable there. We may feel fairly certain that when 

 the case of the bee has been adequately investigated 

 we shall find that the reason why all its fertilised 

 eggs produce females only is because the male- 

 bearing spermatozoa are the ones which degenerate. 



We pass next to consider why it is that in the bee 

 the unfertilised eggs — that is, the virgin or partheno- 

 genetic eggs — always give rise to drones, which are 

 male individuals. Here again we must seek our 

 interpretation by appealing to facts which have been 

 ascertained in phylloxerans and aphids. We have 

 already seen that Professor Wilson and Professor 

 Morgan have observed in certain insects (Wilson) 

 and in phylloxerans and aphids (Morgan) a certain 

 difference in the number of chromosomes in the 

 body cells of the females and males. In the males 

 of insects and aphids and in some phylloxerans there 

 is one chromosome less than in females ; but in other 

 phylloxerans there are two less. Morgan has quite 

 recently shown that there are two kinds of partheno- 

 genetic eggs, one containing a pair of accessory 

 chromosomes and the other not ; that is, one kind 



