HYBRIDISATION AND SELECTION. 77 



Peas rarely become hybridised naturally. 

 According to Darwin, H. Miiller, and Focke, the 

 flowers are little visited by insects in our countries, 

 though the mechanism points to their adaptation 

 for pollination by large bees. 



Rimpau confirms Darwin, H. Miiller, and Ogle 

 as to the self-fertilisation of our cultivated peas. 

 Nevertheless, as is well known, marked varieties 

 have been obtained by artificial crossing by Gart- 

 ner, Knight, Laxton, and others, especially in 

 this country. 



At the same time experiments show that 

 while it is very easy to obtain artificial hybrids 

 of such plants, and there is no fear of natural 

 inter-crossing, the forms are remarkably unstable 

 as yet. Similarly unsatisfactory results were ob- 

 tained with beet. As experiments are still going 

 on, however, we may expect to hear more about 

 these and other results. 



It is probable, from recent experiments by De 

 Vries, Correns, and others, that a remarkable 

 regularity, expressed by Mendel in the form of 

 a law, obtains in the variations which result from 

 hybridising. 



In considering these illustrative cases, it is 

 necessary to thoroughly apprehend that two 

 procedures are involved. In the first place we 

 have the cross-pollination leading to the formation 

 of the hybrid plant by cross-fertilisation. But 

 experience shows that this would lead to very 

 uncertain results if the plant-breeder did not 

 supplement them by the second and extremely 



