14 THE PHYSICAL KINSHIP 



have four-chambered hearts. The red corpuscles 

 in the blood of fishes, frogs, reptiles, and birds, are 

 discs, double-convex, nucleated, and in shape 

 oval or triangular. In man and in all other 

 mammals (except the archaic camel) the red 

 corpuscles are double-concave, non-nucleated, and 

 circular. Man has a diaphragm dividing the body 

 cavity into chest and abdomen, and a shining 

 white bridge of interlacing fibres, called corpus 

 callosum, uniting his cerebral hemispheres. And 

 man is a mammal because, like other mammals, 

 he has, in addition to the qualities already men- 

 tioned, these valuable and distinct characteristics. 



IV. Man a Primate. 



Man is a primate. There are four divisions in 

 the order of primates lemurs, monkeys, apes, 

 and men. But the most interesting and important 

 of these, according to man, is man. Man is a 

 primate because, like other primates, he has arms 

 and hands instead of fore-legs. And these are 

 important characteristics. It was a splendid 

 moment when the tendencies of evolution, 

 pondering the possibilities of structural improve- 

 ment, decided to rear the vertebrate upon its 

 hind-limbs, and convert its anterior appendages 

 into instruments of manipulation. So long as 

 living creatures were able simply to move through 

 the airs and waters of the earth and over the 

 surface of the solids, they were powerless to 

 modify the universe about them very much. But 

 the moment beings were developed with parts of 



