LIFE AND LIVING BEINGS 7 



animals, or be entirely suspended, as in seeds. This state of 

 suspension of life, of latent life as it were, reminds us of a 

 machine that has been stopped, but which retains its form 

 and substance unaltered, and may be started again whenever 

 the obstacle to its progress is removed. 



During the whole course of its life a living being is 

 intimately dependent on its entourage. For example, the 

 phenomena of life are circumscribed within very narrow limits 

 of temperature. A living organism, consisting as it does 

 essentially of liquid solutions, can only exist at temperatures 

 at which such solutions remain liquid, i.e. between 0° C. and 

 100° C. Certain organisms, it is true, may be frozen, but their 

 life remains in a state of suspension so long as their substance 

 remains solid. Since the albuminoid substances which are a 

 necessary component of the living organism become coagulated 

 at 44° C, the manifestations of life diminish rapidly above this 

 temperature. The intensity of life may be said to augment 

 gradually as the temperature rises from 0° to 40°, and then to 

 diminish rapidly as the temperature rises above that point, 

 becoming nearly extinct at 60° C. 



Another condition indispensable to life is the presence of 

 oxygen. Life, compared by Heraclitus to a flame, is a com- 

 bustion, an oxydation, for which the presence of oxygen at a 

 certain pressure is indispensable. There are, it is true, certain 

 anaerobic micro-organisms which apparently exist without 

 oxygen, but these in reality obtain their oxygen from the 

 medium in which they grow. 



Life is also influenced by light, by mechanical pressure, by 

 the chemical composition of its entourage, and by other 

 conditions which we do not as yet understand. In each case 

 the conditions which are favourable or noxious vary with the 

 nature of the organism, some living in air, some in fresh water, 

 and others in the sea. 



Formerly it was supposed that the substance of a living 

 being was essentially different from that of the mineral world, 

 so much so that two distinct chemistries were in existence — 

 organic chemistry, the study of substances derived from bodies 

 which had once possessed life, and inorganic chemistry, dealing 



