PLANT HYBRIDIZATION BEFORE MENDEL 93 



change these habits by changing the male ; but always without success, 

 and I have, in some instances, observed the offspring of the one sex, 

 though obtained from different males, to exceed those of the other in 

 the proportion of five or six and even seven to one. When on the con- 

 trary, I have attended to the numerous offspring of a single bull, or ram, 

 or horse, I have never seen any considerable difference in the number of 

 offspring of either sex." (3c, pp. 397-8.) 



This interesting empirical observation is quoted as being of his- 

 torical interest, and the observation regarding the difference in 

 the reciprocal apple crosses is worth preservation. 



Knight sums up his practical views upon the relation of the 

 science of botany to the breeding of plants in the following 

 words : 



"I cannot dismiss the subject, without expressing my regret, that those 

 who have made the science of botany their study, should have considered 

 the improvement of those vegetables which, in their cultivated state, af- 

 ford the largest portion of subsistence to mankind, and other animals, 

 as little connected with the subject of their pursuit. Hence it has hap- 

 pened that whilst much attention has been paid to the improvement of 

 every species of useful animals, the most valuable esculent plants have 

 been almost wholly neglected. But when the extent of the benefit which 

 would arise to the plants, which, with the same extent of soil and labor, 

 would afford even a small increase of produce, is considered, this subject 

 appears of no inconsiderable importance. . . . The improvement of ani- 

 mals is attained with much expense, and the improved kinds necessarily 

 extend themselves slowly; but a single bushel of improved wheat or peas 

 may in ten years be made to afford seed enough to supply the whole 

 island." (3a, p. 204.) 



Focke, in his Pflanzenmischlinge," pp. 432-3, gives the follow- 

 ing summary of Knight's services to the science and practice of 

 hybridization : 



"Toward the end of the eighteenth century, a man appeared, whose 

 works have been of particular significance for the knowledge of fertiliza- 

 tion and crossing, Thomas Andrew Knight, the celebrated fruit and vege- 

 table breeder. Starting with the successful efforts of the animal breeders, 

 he came upon the thought whether it was not possible to improve do- 

 mestic animals through crossing the races, to obtain more admirable sorts 

 of economic plants. Without knowing anything of Kolreuter, he began 

 his experiments with fruit trees, and from 1787 on, with peas, with which 

 he was naturally able much earlier to turn out definite results. The pro- 

 geny of his crossed races of peas gained extraordinarily in vigor and yield. 

 Already in 1799 ('Phil. Trans.,' 1799, Part I, p. 202), Knight was able to 

 express the principle, that nature intended that a sexual intercourse 

 should take place between neighboring plants of the same species. He 

 laid down this principle through his results in individual and race crosses, 

 especially in the genus Pisum." 



