LECTURE VII 



THE INFLUENCE OF THE " ORIGIN OF SPECIES " ON 

 BOTANICAL RESEARCH 



THE Origin of Species appeared most opportunely, for it 

 supplied the key required to elucidate the wonderful 

 discoveries that had been made by Hofmeister. As I 

 have already told you, his investigations led to the 

 recognition of a uniformity in life-history throughout 

 the whole plant world, and at last united in one continuous 

 series the Cryptogams and Phanerogams. The key was 

 progressive evolution: the result was a phylogenetic 

 classification based on alternation of generations. The 

 vast importance of physiology now became evident in the 

 light of adaptation to changes of environment. Living 

 plants had now to be pictured as a host of units in com- 

 petition with each other for food and for space in which 

 to live and multiply, fighting for existence, on the one 

 hand against each other, even more especially against 

 their own kith and kin, and on the other against un- 

 favourable conditions of the environment. Every struc- 

 tural detail had to be explained in terms of vital needs, 

 and morphology and its extension, anatomy, were seen 

 to be the concrete and visible manifestations of physio- 

 logical adaptation. 



The dogma of the constancy of species, that had 

 been an incubus on the shoulders of all the taxonomists 

 of past generations, and that had driven them to all 

 sorts of subterfuges in their efforts to reconcile self- 

 evident facts with preconceived ideas, at last begins to 



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