in Hybridisation 43 



Experiments which were made with several members of this 

 family led to the result that the genus Pisum was found to 

 possess the necessary conditions. 



Some thoroughly distinct forms of this genus possess 

 characters which are constant, and easily and certainly 

 recognisable, and when their hybrids are mutually crossed 

 they yield perfectly fertile progeny. Furthermore, a dis- 

 turbance through foreign pollen cannot easily occur, since 

 the fertilising organs are closely packed inside the keel and 

 the anther bursts within the bud, so that the stigma 

 becomes covered with pollen even before the flower opens. 

 This circumstance is of especial importance. As additional 

 advantages worth mentioning, there may be cited the easy 

 culture of these plants in the open ground and in pots, and 

 also their relatively short period of growth. Artificial 

 fertilisation is certainly a somewhat elaborate process, but 

 nearly always succeeds. For this purpose the bud is 

 opened before it is perfectly developed, the keel is removed, 

 and each stamen carefully extracted by means of forceps, 

 after which the stigma can at once be dusted over with the 

 foreign pollen. 



In all, thirty-four more or less distinct varieties of Peas 

 were obtained from several seedsmen and subjected to a 

 two years' trial. In the case of one variety there were 

 remarked, among a larger number of plants all alike, a few 

 forms which were markedly different. These, however, did 

 not vary in the following year, and agreed entirely with 

 another variety obtained from the same seedsmen ; the 

 seeds were therefore doubtless merely accidentally mixed. 

 All the other varieties yielded perfectly constant and 

 similar offspring ; at any rate, no essential difference was 

 observed during two trial years. For fertilisation twenty- 

 two of these were selected and cultivated during the whole 



