THE PROPERTIES OF PROTOPLASM 17 



stability respectively mean. The incidents ex- 

 pressible by vitality must be as diverse and as 

 widely scattered throughout organic nature as are 

 the capabilities and potentialities of living matter. 

 There may be, I believe there are, as many mani- 

 festations of functional inertia as there are of 

 affectability ; neither property can explain too 

 much ; between them they have to explain the 

 whole realm of vitalised existence ; and if they 

 do not do so, nothing else at present is capable 

 of doing it. To neither property alone can the 

 multitude of vital phenomena be logically referred. 

 If there be a property of inertia such as I have 

 described, it should be capable of demonstration in 

 the cell, in the tissue, in the organ, in the system, 

 in the organism, in the species, in the nation and in 

 the race. It must underlie psychological as well as 

 physiological facts, mental behaviour as well as 

 bodily conditions. There must be a metabolic 

 inertia expressible in the vital unit as well as in 

 the vital whole the animal or plant, and in 

 the social unit as well as in the social whole the 

 community or race. 



[I need hardly say that living organisms have inertia of mass, 

 inertia in the ordinary sense. It is due to our mass (inertia of 

 rest) that we fall backwards when the electric car starts suddenly 

 and owing to our inertia of motion (momentum) that we fan 

 forward when the car stops suddenly. By our inertia of mass 

 in motion, we fall forwards if our foot catches in an obstacle 

 when we are running, and in this way a child trips more readily 

 than an adult owing to its centre of gravity being relatively 

 a good deal higher due to the greater relative size and weight 

 of the head in the child, I need scarcely say, finally, that the 



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