THE UNITY OF LIFE 213 



176. Control in higher animals. When a simple animal ad- 

 justs itself to food particles, or escapes from an enemy, we are 

 impressed by the fitness of its action. We are also impressed by 

 the activities of a plant in relation to its surroundings. Never- 

 theless we cannot say that plants and simple animals act "on 

 purpose," no matter how useful the processes are. 



For one thing, we know that we can reproduce the parts of 

 many of these processes by means of physical and chemical ap- 

 paratus. For another thing, purpose means nothing unless 

 we assume the presence of a mind like our own, which can 

 have a purpose; and we cannot assume this from what we 

 know of these organisms. Indeed, most of the acts committed 

 by ourselves can be shown to be without purpose, even where 

 they are of value to the organism. We therefore have no right 

 to attribute purpose to organisms of whose minds we know 

 nothing. What they do, like most of what we do, comes from 

 being the kinds of organisms they are ; they cannot help it. 



At the same time, we know that in our own case it has been 

 possible to select lines of conduct that do not come naturally. 

 In so doing we obtain from the world many advantages that we 

 should not otherwise have ; or we escape many dangers or in- 

 conveniences to which we should otherwise be exposed. We find 

 great variety in the manners and customs of different races, as 

 well as great differences in modes of living even in our own 

 home town. These suggest that we have a certain control both 

 over the workings of our bodies and over our environment ; or, 

 rather, we have a certain control over our environment by 

 means of the control which we have over our own actions. This 

 control of our own activities comes from the nervous system. 



THE UNITY OF LIFE 



I. All life is one 



All living things are alike 



In depending upon certain materials and conditions 



In carrying on certain processes 

 Everything going on in an organism is related to the life of that 



organism 



