254 PHYSICAL EXPRESSION. 



thing, and is not therefore within the range of our 

 consideration, but we can deal with the expression 

 of thought. We know that a man has thought by 

 what he subsequently says and does. While deeply 

 thinking there is but little movement,, but little 

 outward expression ; the kinetic functions of the 

 brain are suspended while it is performing its 

 mental functions. The subsequent series of actions, 

 the sequential modification of spontaneous move- 

 ments,, and the susceptibility to new reflexes and 

 fresh impressions these are the expression of the 

 unknowable process thought or mentation. 



Physical study of mind. Table of brain pro- 

 perties necessary factors of the faculty of mentation. 

 It is interesting to notice that the properties of the 

 brain which indicate its potentiality for mentation, 

 are analogous to properties found in plants and 

 inorganic things : 



Impressionability: phonograph, telephone (pp. 

 18, 19). 



Retentiveness : phonograph (p. 19). 



Reflex action : Drosera (p. 152). 



A series of actions : (a) resulting from an apparent 

 force, paper organ machine ; folding of leaf of 

 Mimosa; (6) a combination or aggregation of 

 actions as the result of a stimulus. 



Change of function : see p. 39. 



Inhibition : see p. 94. 



Nutrition : see p. 234. 



