120 BOTANY AND INTENSIVE CULTIVATION 



to the third and seeks to preserve plants from disease 

 by improving his methods of cultivation. Both 

 are right yet neither is wholly wise, and there is 

 much room in the world for a race of mycologists 

 who not only discover how to cure plants but 

 know how to cultivate them. Biffen seized upon 

 the second of the three factors and envisaged 

 immunity not as an accident but as a grace a 

 quality inherent in a plant by virtue of which it 

 actively or passively resists a given kind of evil. 

 Coeval with this stream of knowledge and like 

 it having its sources in the remote fastnesses of 

 pure science another stream commenced to carve 

 out a course for itself through the hard rock of 

 ignorance in which all knowledge has to make 

 and maintain its way. Never was mountain 

 torrent more turbulent than was the science of 

 heredity in its early course. But as the torrent 

 issues in its lower reaches into the navigable river 

 so the science of heredity controlled and canalised 

 by Mendel became a practicable and fertile stream 

 of knowledge. Thanks to the genius of this man 

 we know that if we will discover the laws of inheri- 

 tance we must fix our attention not on the organism 

 as a whole but upon one and another in turn of 

 the many attributes or characters of that organism. 

 Thus disintegrated the problem of inheritance be- 

 comes susceptible of solution by the method of 

 experiment. By applying that method Mendel 

 discovered the simple laws which govern the mode of 



