PLANT AFFINITIES 229 



men branched from a common stem with the 

 direct ancestors of the gorilla. There has been 

 no blending of blood in the intervening centuries. 

 Cats have been cats and dogs dogs from geologi- 

 cal epochs so remote that we hesitate to guess 

 their span in terms of years. So the intimate 

 chemical qualities that denote man or ape or cat 

 or dog, each in contradistinction to all the others, 

 must have been transmitted unmodified through 

 countless 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 these are the facts. 



"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, 



