192 Life and Matter [chap. x. 



portions of their substance or move their 

 whole bodies towards the fragment, thus 

 beginning the act of " hunting " ; and the 

 incipient locomotory power can be ex- 

 tended till light and air and moisture and 

 many other things can be sought and 

 moved towards, until locomotion becomes 

 so free that it sometimes seems apparently 

 objectless mere restlessness, change for 

 the sake of change, like that of human 

 beings. 



The power of locomotion is liable, how- 

 ever, to introduce the cell to new dangers, 

 and to conditions hostile to its continued 

 aggregate existence. So, in addition to the 

 sense of food and other desirable things 

 ahead, it seems to acquire, at any rate when 

 still further aggregated and more developed, 

 a sense of shrinking from and avoidance of 

 the hostile and the dangerous, a sense as it 

 were of "pain." 



And so it enters on its long career of 

 progress, always liable to disintegration or 

 " death " ; it begins to differentiate portions 



