PLANT AFFINITIES 



qualities that denote man or ape or cat or dog, 

 each in contradistinction to all the others, must 

 have been transmitted unmodified through count- 

 less thousands of generations. 



"It taxes credulity to believe that such intan- 

 gible properties could be transmitted unmodified 

 through the blood streams of such myriads of 

 individuals; but the evidence of the test-tubes 

 proves that this has been done. 



"What makes the marvel greater is the fact 

 that the bodies of the animals have meantime 

 been so modified as to develop utterly divergent 

 species — ^for example, the lion, the tiger, the 

 puma, the leopard, and the house cat; different 

 types of dogs, wolves, foxes and their allies. But 

 in each case some intangible quality of the blood 

 remains unchanged to prove the common origin. 

 Blood is indeed thicker than water." 



The bearing of these extraordinary experi- 

 ments upon the case in hand will be obvious. 



If animals carry in their veins generation after 

 generation, through untold thousands of years, 

 these intimate chemical conditions, then the same 

 thing may well be supposed to be true of plants. 

 And so the afiBnity shown between species that 

 can be hybridized, and the antagonism between 

 species that refuse to hybridize, can be explained 

 on the basis of a fundamental intrinsic quality of 



[51] 



