THE ORGANISM AS A NATURAL THING 13 



complex of inanimate things are the " organic " carbon- 

 compounds and the siHcates of which igneous rocks are composed 

 and the molecules of these silicates may contain only some dozens 

 of atoms. But the molecules of proteins in the bodies of animals 

 and plants are composed of tens of thousands of atoms. 



X. Some kinds of chemical compounds are present only in the 

 bodies of organisms. Proteins, fats and carbohydrates are the 

 typical chemical substances that compose the bodies of organisms 

 and these substances do not exist among inanimate things. They 

 can be found in artifacts, that is, they have been made by organisms. 

 Proteins, fats and carbohydrates may now be regarded as having 

 been synthesized by experimental chemists, but that means that 

 they have been produced, or assembled by living organisms. It 

 is immaterial to this description that the green plant synthesizes 

 sugar automatically (and easily) while the chemist does so deliber- 

 ately (and with difficulty). 



5. ON THE ORGANISM AND ITS ENVIRONMENT 



So far we have regarded organisms as natural things which we 

 can detach from nature in general and study separately from all 

 other natural things. This, however, is not true, though it has 

 been a convenient (and necessary) step in our descriptions. 

 Organisms cannot exist apart from the other natural things 

 which surround them and exist contemporaneously with them. 

 An organism is not a thing in the sense that a diamond, a physically 

 dead planet, or a rock is a thing : it is " something happening." 

 Since it is a flux of materials we must consider along with it all 

 those other natural things with which it has traffic, or relations 

 of any kind. If we were strictly to isolate an animal from its 

 environment it would die in a short time — a very few minutes in 

 the case of a mammal and a little longer in the case of some lower 

 animals. Obviously a mammal must respire and respiration 

 involves the environing oxygen of the atmosphere. 



5«. The Physical Status of the Organic Environment. 

 We have seen that in the passage of nature natural things become 

 '' made." It is easy to contemplate the complete making of a 

 part of the universe, say the solar system. The time must come 

 when the internal energy of the sun will be exhausted, or so 

 nearly so that it will no longer emit radiation. By that time 



