AS THE BIOLOGIST SEES IT 



reactions differing from those of the 

 blood of other higher mammals, is a 

 notable modern addition to the biological 

 evidence for anthropoid and human rela- 

 tionships. For the same identities or 

 close similarities in blood character occur 

 in the case of other kinds of animals well 

 known to be closely related, as the wolf 

 and dog, or the horse and ass, and do 

 not occur when the blood of two less 

 closely related animals is tested. 



A less important and less well-known 

 added bit of evidence is one that came 

 under my own observation a few years 

 ago during the course of some study of 

 certain highly specialized external insect 

 parasites of man and some other mam- 

 mals. In this study it became apparent 

 that the kinds of these parasites character- 

 istic of and limited to men and apes are 

 more closely related to each other than 

 they are to parasitic kinds characteristic 

 of the other quadrumana or of any other 

 mammals. That is, the parasites of the 

 apes are even less closely related to those 

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