512 



PLANT BREEDING 



Hybrids have been made between the very long-fibered fine sea- 

 island species and the ordinary upland species, and after six 

 generations of selection and careful cultivation some valuable 

 hybrid varieties seem to have been developed. 



489. Results of hybridizing wheat. The flowers of wheat 

 are naturally self-pollinated,- -that is, the stamens of each flower 

 commonly discharge their pollen upon the feathery stigma of 

 their own flower as soon as the pollen sacs open. This fact 

 makes hybridization much more effective in producing variation 



FIG. 382. Variation in wheat, the hybrid offspring of hybrid parents 



After figure redrawn from Transactions of the Highland and Agricultural 



Society of Scotland 



in wheat than in plants which are generally cross-pollinated : 

 for in the case of wheat any kind of cross pollination, and 

 especially that between markedly different varieties, may be 

 said to give a sort of shock to the operation of reproduction, 

 and thus produce abundant variation. The details of the 

 process of artificial pollination need not be given. It is suc- 

 cessful in a large proportion of cases, and the offspring may be 

 of many types, as shown by Fig. 382. It is found that after 

 the fourth generation an occasional plant may be found which 



