6 THE PHYSICAL KINSHIP ' 



bodies of all other animals. And the cells in 

 the body of a human being are not essentially 

 different in composition or structure from the cells 

 in the body of the sponge. All cells are composed 

 primarily of protoplasm, a compound of carbon, 

 hydrogen, nitrogen, and oxygen. Like all other 

 animals, man is incapable of producing a particle 

 of the essential substance of which his body is 

 made. No animal can produce protoplasm. This 

 is a power of the plant, and the plant only. All 

 that any animal can do is to burn the compounds 

 formed in the sun-lit laboratories of the vegetable 

 world. The human skeleton, like the skeletons of 

 nearly all other animals, is composed chiefly of 

 lime — lime being, in the sea, where life spent so 

 many of its earlier centuries, the most available 

 material for parts whose purpose it is to furnish 

 shape and durability to the organism. Man grows 

 from an egg. So do all creatures of clay. Every 

 animal commences at the same place — in a single, 

 lowly, almost homogeneous cell. A dog, a frog, 

 a philosopher, and a worm cannot for a long 

 time after their embryonic commencement be 

 distinguished from each other. Like the oyster, 

 the ox, the insect, and the fish, like all that live, 

 move, and breathe, man is mortal. He increases 

 in size and complexity through an allotted period 

 of time; then, like all his kindred, wilts back into 

 the indistinguishable flux from which he came. 

 Man inhales oxygen and exhales carbon dioxide. 

 So does every animal that breathes, whether it 

 breathe by lungs, gills, skin, or ectosarc, and 



