78 ORGANIC EVOLUTION 



whether the varieties of the two animals are different. 

 The blood of any kind of dog will not affect the 

 blood of any other kind of dog. Directly, however, 

 there is introduced the specific difference -— the 

 difference of species — this cell-dissolving action is 

 found to occur. We thus have a new and subtle 

 specific test for blood. A given blood-stain upon 

 the clothes of a suspect may be human, as the 

 police allege, or canine, as the accused alleges. 

 The truth can be ascertained without reference to 

 circumstantial evidence. If a solution of this blood- 

 stain is found to exercise no action upon a few drops 

 of canine blood, but is found to dissolve the cells of 

 human blood, the accused is vindicated. The blood 

 is canine, as he states, else canine blood would not 

 consort with it ; not human, else human blood 

 would be unaffected by admixture with it. 



What, now, if we apply this test to the blood of 

 man as compared with the blood of the ape? 1 

 The astonishing fact, to which I think the word 

 bizarre may fairly be applied, is that this specific 

 test fails when thus applied. I have said, " the 

 blood of the ape," but I must correct myself. Hans 

 Friedenthal of Berlin has shown that human blood, 

 when mixed with the blood of the loicer apes, has a 

 poisonous effect on the latter : the serum of the one 

 destroys the blood-cells of the other. But this does 

 not happen when human blood is mixed with that 

 of the anthropoid ape. Regarded in the light of 

 the facts we have already detailed, we cannot but 



1 The whole subject is so new that I must not be regarded as 

 speakiDg with any air of finality. These tests may also be performed 

 in a much more roundabout but much more accurate fashion. (For 

 a brief account of this see Metchnikoff s " Nature of Man.") 



