84 CROON I AN LECTURES 



system are the other correlated actions heat, 

 electricity, nutrition, contractility, and sensi- 

 bility. These must increase or diminish as the 

 action of oxygen increases or diminishes ; and 

 the questions which arise as to the mode and 

 extent of the convertibility of any one of these 

 motions into other modes of motion have to be 

 determined by further investigation. 



Stimulants, tonics, and evacuants, may, per- 

 haps, not only take part directly in the motions 

 of any part, but they may also promote or 

 retard the conversion of one motion into other 

 motions. 



Specifics and alteratives may, directly as 

 well as indirectly, change the motions in the 

 system. 



And sedatives and narcotics may have the 

 same double action in retarding or stopping 

 the motions that take place. 



This view will almost lead us to consider all 

 medicines as alteratives, and, if so, we may 

 perhaps place stimulant and sedative medi- 

 cines at the two extremes of the alterative 

 actions ; the stimulants giving rise to the 

 greatest increase of motion, and the sedatives 

 allowing the least motion or the nearest ap- 



