268 PHYSICAL EXPRESSION. 



As to Qiwiitity ; if we can observe and measure 

 this at each period of time, we thus determine the 

 total quantity of the function. To describe the 

 quantity of a function, it is necessary to adopt a 

 unit of quantity. If any unit of quantity can be 

 found as common to two dissimilar functions, a 

 comparison may be made between them as to 

 quantity. 



As to Kind ; it is not convenient to consider this 

 here. In some cases the " kind " may be described 

 in terms of time, and quantity of the function or 

 action. Nerve-muscular movement has practically 

 only two attributes time and quantity. What we 

 commonly call "kinds of movement," are usually 

 series of movements, each separate movement 

 having its own time and quantity. It may be here 

 remarked that one of the great differences between 

 the properties of living and non-living things is, 

 that in the former properties often vary in time, 

 quantity, and kind ; whereas in non-living things 

 a property, such as hardness, is more permanent 

 in its duration, and more unchangeable, except 

 under the agency of obvious afferent forces. Iron 

 retains its hardness except under the influence of 

 heat. 



When we come to consider the attributes of 

 growth, or trophic action, and movement, or kinetic 

 action, in two or more subjects, other points present 

 themselves to our notice. 



As to the attribute Time of growth or movement 

 in two subjects. The time of growth or movement 

 in each subject may coincide, or it may not coincide. 



