156 THE SURVIVAL OF THE UNLIKE. [v. 



wood and bark, the motions of tendrils, and the like. In 

 purely horticultural lines, he took hold of the common 

 perplexities of the time and endeavored to solve them. 

 He made studies touching the best methods of cultivat- 

 ing many plants, and he was amongst the first to make 

 really scientific experiments with the gi'owing of plants 

 under glass. He gave particular attention to physi- 

 ology and methods of grafting, and appears to have been 

 the first to perfect the method of root -grafting which is 

 now in common use. The activity and variety of his 

 interests during the first third of the century attracted 

 the widest attention, and placed him at the very front of 

 English - speaking horticulturists . 



But Knight did his greatest work in the direction of 

 ecological studies, through which he desired to discover 

 the best means of improving plants. He took up the 

 vexed questions of the running out of varieties, and he 

 made great efforts to produce new ones. It will thus be 

 seen that the greatest problems which presented them- 

 selves to Knight were exactly those which appealed to 

 Van Mons. But the two men were unlike in temper. 

 Van Mons, as we have seen, projected a general theory 

 and then set out to prove it. Knight, on the contrary, 

 began an inquisitive study of nature, and never arrived 

 at a general theory of the amelioration of plants. It is 

 true that he had hypotheses for some of the minor prob- 

 lems which he undertook, but this is essential to any 

 efficient study. An hypothesis is the line to which the 

 axman works. But these hypotheses of Knight's were 

 never of the dogmatic kind, which apply themselves with 

 unvarying assurance to large classes of facts. One of 

 these hypotheses is worth mentioning here, because it is 

 so closely like that held by Van Mons. He was con- 



