HYBRIDISATION AND SELECTION. 71 



position on the stigmas, and the caps replaced. 

 The pollination is repeated occasionally, and care 

 taken that no uncrossed flowers develop later. In 

 this way a few seeds or grains are got to start with. 

 This would be the place to introduce an account 

 of the enormous advances made by the botanists 

 of the last decade or two in the study of the micro- 

 scopic phenomena of fertilisation. Without going 

 into details which would more than occupy all 

 the space at command I may recall the discoveries 

 of Strasburger and his pupils, and of Guignard, 

 which have supplemented the earlier discoveries of 

 De Bary, Cohn, and Hofmeister, by establishing the 

 facts that the essential point in fertilisation is the 

 fusion of two nuclei, and the bringing together in 

 the fused mass of two extremely minute thread- 

 like coiled bodies, the so-called chromatosomes or 

 filaments, one of which is derived from the male 

 and the other from the female parent. The par- 

 ticulars as to the marvellous adaptations to secure 

 the union of these two infinitesimally minute 

 threads, their behaviour immediately before and 

 after union, and many other points must be passed 

 over, as I have only space to emphasise the one 

 crowning discovery that these tiny filaments of 

 nuclear substance are the material carriers of all 

 the hereditary properties of the parents to the 

 young plant which their union initiates. 



It must not be supposed that the above state- 

 ments are based on any meagre foundation of 

 facts. The attraction of the fusing nucleated 

 masses had been demonstrated over and over 



