140 



HEREDITY AND EVOLUTION IN PLANTS 



Darwin's teaching, which freed men's minds from the 

 shackles of preconceived notions, founded, not on observa- 

 tion of facts, but on a more or less blind acceptance of 

 current theological suppositions, or on the teachings of 

 ancient writers, the facts of distribution had a far different 

 significance than they were seen to possess when men began 

 to interpret the present state of nature as being the result 



FIG. 70. Alexander von Humboldt (1769-1859). Founder of the 

 science of plant .geography. 



of the operation of natural causes; by most students they 

 had been regarded as so much information, like the matter 

 in a guide book, but pointed the way to no larger conception 

 or generalization, so far as historical evolution was con- 

 cerned. To find giant redwood trees exclusively in Cali- 

 fornia meant nothing, except that they were created there 

 and nowhere else, and had never spread; to find the bracken 



