20 THE ORIGIN OF LIFE 



imagined to-day," and then proceed to give rea- 

 sons for this belief. Here, then, apart even from 

 de novo origination of the bacteria, there is the 

 admission by celebrated bacteriologists of doctrines 

 like mine which are commonly deemed altogether 

 unorthodox. Still, as Lehmann and Neumann 

 say, there are many indications of an approaching 

 change of view. 1 



But for biologists also, as I have already pointed 

 out when speaking of Heterogenesis, my views are 

 similarly unpopular, and to botanists especially 

 the results recorded in this memoir will seem 

 well-nigh incredible. Biologists have been led to 

 believe, as Herbert Spencer and others have sug- 



1 As further evidence of the truth of this statement the reader 

 may be referred to an article by M. C. Potter entitled " Bacteri- 

 ological Research in Phytopathology " (Science Progress, Oc- 

 tober, 1910, p. 209), in which he says: "With a knowledge of 

 the fact that nutrition may so alter a facultative saprophyte that 

 it becomes a virulent parasite, while through other nutritional 

 changes its virulence may be entirely lost; and, further, that 

 the same influence operates in rendering the host more or less 

 susceptible, we have the key to one of the most important de- 

 termining factors in the epidemic diseases of plants." Such 

 are the views that skilled experts are now beginning to enun- 

 ciate. They are in marked contrast to popular doctrines con- 

 cerning communicable diseases, in accordance with which a 

 Cambridge professor, when speaking of Tuberculosis and the 

 very great importance of minimising its spread by means of 

 contagion, has lately ventured to say (The Times, Sept. 20, 

 1910), "the disease can no more be developed than can turnips 

 spring up where no seed has been sown." 



