118 THE NEW PHYSIOLOGY. 



both of which we know to be only sensibly true when 

 " bodies " are at more than a certain distance from 

 one another. This superficial knowledge is of inestimable 

 practical value in spite of its superficiality. In chemistry 

 we go deeper, and consider what happens when what we 

 interpret as matter is in intimate contact with other 

 matter. In this region we see beyond the superficial 

 generalisations of mechanical physics. In biology we 

 see further still : we make use of the whole of the 

 superficial generalisations presented by physics and 

 chemistry, but we have to interpret them afresh, in view 

 of the new facts which appear in biology, just as we 

 have to re-interpret biological generalisations in view 

 of the new facts revealed in still higher branches of 

 knowledge, such as psychology and ethics. 



I know well that this is not the view to which popular 

 natural science has accustomed the world in recent 

 times ; but I am convinced that it is the only view 

 which can be reconciled with the facts and with the 

 implicit claims of every kind of real scientific investi- 

 gation. Popular natural science has suffered severely 

 from what, in vulgar language, is called " swollen 

 head " ; and the sooner this is generally recognised 

 the better. When we refer back to actual observation 

 the abstractions of popular natural science appear in 

 their proper light. 



I have tried to show that there neither is nor can be 

 any mechanistic explanation of heredity and nutritive 

 activity, which are integral parts of Darwin's theory. 

 I now wish to examine more closely the fact of variation, 

 which is another integral part. A variation in the 

 biological sense is something that has relative permanence 



