PHENOMENA AND CONDITIONS OF LIFE 29 



unless its life-functions are to cease temporarily or permanently. 

 Whilst the substance of the body is renewed from the food, the 

 matter that has become decomposed and useless is voided. This 

 continued breaking-down and building-up of organic substance 

 is called metabolism ; it is on this process that all the life 

 phenomena of animals and plants rest, and it is therefore 

 generally regarded as a specific function of life. 



According to Verworn, however, metabolism is only a charac- 

 teristic which distinguishes the living organism from the dead, 

 but not from the inorganic substances, for it is possible to 

 observe the same process in inorganic bodies. As an example 

 this scientist chooses the behaviour of nitric acid in the manu- 

 facture of so-called English sulphuric acid. If we bring together 

 nitric acid with the anhydride of sulphurous acid, the sulphurous 

 acid takes away oxygen from the nitric acid, thus becoming sul- 

 phuric acid, while the nitric acid becomes hyponitric acid. If 

 we now regularly admit fresh air and water, nitric acid continues 

 to develop from the hyponitric acid, and gives off part of its 

 oxygen to new volumes of sulphurous acid, so that the mole- 

 cule of the nitric acid is continually being disintegrated by 

 giving off oxygen, and restored by absorbing oxygen. In this 

 manner we are able, with a definitive quantity of nitric acid, to 

 change unlimited quantities of sulphurous acid into sulphuric 

 acid. Verworn thinks, therefore, that the process observed here 

 in the simplest form, that is, in a simple chemical compound, 

 the succession of decomposition and reconstruction of the sub- 

 stance with taking-in and giving-off matter, corresponds in every 

 detail to the metabolism of organism. 



Bat it seems to me that in spite of the apparent similarity 

 there is a fundamental difference in these two processes, for 

 whilst in an organism metabolism proceeds automatically, it 

 proceeds here on the supposition that the constant access of 

 air and water is being duly regulated ; in other words, it proceeds 

 with the assistance of a rational being. As soon as this assis- 

 tance fails, as soon as the supply of air and water is not so 

 regulated as to bring the hyponitric acid in a certain manner 

 and in certain proportions successively into contact with air, 

 sulphurous acid and water, metabolism ceases. But it is in 

 the spontaneity that the essence of the life-processes rests, and 



