130 THEORETICAL BIOLOGY 



It is not only the creatures with weapons, but also the 

 defenceless ones, that are involved in the struggle. Their 

 protection lies either in their swiftness or in their numbers. 

 The most striking instance of this is that many more eggs are 

 laid than young are hatched, because the great proportion of 

 eggs are always sacrificed to enemies. Here we see clearly 

 that a new sort of conformity with plan comes in, which 

 hitherto we have not considered ; this is conformity with plan 

 on the part of the species, of which we shall have more to say 

 later on. 



But first we must confine ourselves with conformity 

 with plan on the part of the individual. 



One thing has become evident from our treatment of the 

 problem up to this point, i.e. that biology is concerned only 

 with conformity with plan, and that the study of causality 

 comes into the question only in so far as it contributes to that 

 investigation. All the things that play a part in the function- 

 circle of an animal we consider only from the point of view 

 of function. This means that we have to do exclusively with 

 implements, and never with objects. The stone that a beetle 

 climbs over is merely a beetle-path, and does not in any 

 way belong to the science of mineralogy. Its weight and its 

 material properties, such as atomic weight or chemical valency, 

 are for us matters of indifference. These are all of them 

 accompanying properties, which we may overlook, since we 

 are interested only in the leading properties of the form and 

 hardness of the stone. 



In the body of the subject, physical and chemical causality 

 plays a much more important part, because here the dis- 

 tinction between leading and accompanying properties dis- 

 appears, since all the material properties are comprehended in 

 the framework of the living organism. And so, when we are 

 trying to grasp the chemistry or the physical properties of an 

 animal, we are certain of meeting with a life-property ; but 



