GENERAL CONDITIONS OF BRAIN-ACTIVITY. 103 



be in the remotest degree compared with the stream of 

 thought that accompanies the brain's material secretions. 



There remains another feature of general brain-physi- 

 ologj, and indeed for psychological purposes the most 

 important feature of all. I refer to the aptitude of the brain 

 for acquiring habits. But I will treat of that in a chapter 

 by itself. 



