xm" CERTAIN COMPLICATIONS 157 



that they normally produce seed by a peculiar 

 process of parthenogenesis. It is possible to take 

 an unopened flower and to shear off with a razor all 

 the male organs, together with the stigmata through 

 which the pollen reaches the ovules. The flower, 

 nevertheless, sets perfectly good seed. But the cells 

 from which the seeds develop are not of the same 

 nature as the normal ova of a plant. They are 

 not gametes, but retain the double structure of the 

 maternal cells. They are rather to be regarded as 

 of the nature of buds which early become detached 

 from the parent stock to lead an independent exist- 

 ence, and, like buds, they reproduce exactly the 

 maternal characteristics. The discovery of the true 

 nature of this case was only rendered possible by 

 the development of the study of cytology, and it 

 was not given to Mendel to live long enough to learn 

 why his hybrid Hieraciums all bred true. 



