INTRODUCTORY ' : THE ANIMAL ORGANISM 13 



dependently of its surroundings. Its whole constitution 1 is due, not 

 only to the properties inherent in it when it was formed by its parent, 

 but also to all the influences by which it is continually being affected 

 from its first moment, some of which, such as food and a certain 

 temperature, are essential to its existence and development, while all 

 bring about permanent alterations in it by its own activity in responding 

 to them. Thus the existence and peculiar features of a bird are due to 

 the warmth which brings about its formation in the egg, as well as to 

 those qualities in the egg which cause it to give rise to a bird ; and 

 every child, in response to the voice of its elders, learns facts and sets 

 up habits which affect its mental constitution throughout life. If, 

 therefore, in virtue of its constitution, there occur in the living animal 

 actions which are not the direct result of any external stimulus, such 

 actions have nevertheless not occurred independently of the influence 

 of its surroundings, since the constitution itself is the result of a history 

 in which that influence has played an essential part. In so far as the 

 surroundings have a share in forming any animal, they have a share in 

 causing its automatic actions. 



We have now dealt with the way in which the life 

 processes arise. From what has been said it 

 ness? l "' ,10SIVe " w iH De clear that, whatever part the organism 

 itself may play in automatism, directly or in- 

 directly, everything that happens in an animal is a reaction 

 to events that have happened outside it. But if the processes 

 which make up life are a reaction to changes in the sur- 

 roundings, they are a reaction of a very special kind. This is 

 quite clear when disintegration within the body is compared 

 with that which may be brought about in lifeless things. 

 (a) When a bonfire is made the energy of the fuel is spent 

 without accomplishing any definite end. When a fire burns 

 in the furnace of an engine its energy is directed towards the 

 working of the engine. We have seen that the expenditure 

 of energy in the body is of this kind. (0) At the same time 

 the result of the working of the bodily machine is different 

 from that of the working of a lifeless engine in that it is 

 directed towards an end in relation to the body itself. When 

 a man seeks food or avoids unfavourable circumstances, 

 when he converses with his friends or strives with his 

 enemies, when he shapes his doings in accordance with 

 warnings received by ear or from print, he is acting in his 

 own interests. He may fail, but the tendency of bis action 



1 The use of the word "constitution" here does not prejudice the 

 question whether the constitution of an animal, as the biologist is con- 

 cerned with it, is a purely physical thing. 



