LIFE 345 



present appears no probability of its being, obtained 

 except from organic substances. Turning to the charac- 

 teristic movements of life, we note that organic substance 

 is conceived as growing differently from inorganic sub- 

 stance. When rrystals increase in size we conceive them 

 to set molecule to molecule, building up from the outside. 

 Organisms, on the other hand, we suppose to grow by an 

 inner growth or the addition of new organic corpuscles in 

 between and not on the surface of the old ones. Life 

 further undergoes cyclical changes or movements in which 

 some process of reproduction or division renews the 

 individual. Lastly, a peculiar environment, certain con- 

 ditions of moisture and temperature are necessary to 

 maintain life. All these characteristics suffice to mark 

 off the organic from the inorganic, and the distinction 

 thus drawn appears to be absolutely rigid.^ There is at 

 the present time, so far as we know, 7io generation of 

 living from lifeless substance. Thus our endeavour to 

 define life has led, through some perhaps not unprofitable 

 byways, to the consideration that the distinction between 

 organic and inorganic is not so marked that we can 

 separate the one from the other by anything but a 

 lengthy statement of secondary characteristics. 



The axiom onine vivicnt e vivo is one which deserves the 

 reader's special attention, for it is closely associated with 

 many important problems on the borderland of biology 

 and physics. In the language of this Grammar, living 

 and lifeless are class names for certain groups of sense- 

 impressions, fundamentally distinguished from each other 

 by requiring for their conceptual description different 

 atomic structures and different types of motion. So far 

 as our present experience goes, there is no routine of 

 sense-impressions which, starting from the lifeless class, 

 concludes with the living class. On the other hand, the 

 converse transition from the living to the lifeless is an 



1 These are the distinctions of biology (see, for example, the article 

 " Biology " in the EiicyclopcBdia Rritannica). Of course a physical statement 

 as to the laws under which organic corpuscles are to be conceived as moving 

 in each other's presence and in that of inorganic corpuscles, might, could it 

 be found, resume many of these characteristics in a simple formula. 



