LIFE 



are the sole factors of biological catalysis. Verworn 

 also points out the analogy between this enzymatic 

 process of metabolism and the inorganic processes of 

 catalysis — for instance, in the manufacture of English 

 sulphuric acid. A small and constant quantity of nitro- 

 muriatic acid, with the aid of air and water, converts an 

 unlimited mass of sulphuretted acid into sulphuric acid 

 without being changed itself; the molecule of the nitro- 

 muriatic acid breaks up steadily by the giving-off of 

 oxygen, and is then restored by the assumption of 

 oxygen. 



The manifold and changeful phenomena of life and 

 their sudden extinction at death seem to every thoughtful 

 man to be something so wonderful and so different from 

 all the changes in inorganic nature that from the very 

 beginning of biological philosophy special forces were 

 assumed to explain it. This was particularly due to the 

 remarkable, orderly structure of the organism and the 

 apparent purposiveness of the vital processes. Hence, in 

 earlier days a special organic force {archcBus insitns) was 

 assumed, controlling the individual life and pressing the 

 "raw forces" of inorganic matter into its service. In 

 the same way a special formative impulse was supposed 

 to preside over the wonderful processes of development. 

 When physiology began to win its independence, about 

 the middle of the eighteenth century, it explained the 

 peculiar features of organic life by a specific vital force. 

 The idea was generally received, and Louis Dumas 

 endeavored thoroughly to establish it at the beginning 

 of the nineteenth century {cf. chapter iii. of the Riddle). 



As the theory of a vital force, or vitalism, plays an 

 important part in the study of the wonders of life, has 

 undergone the most curious modifications in the course 

 of the nineteenth century, and has been lately revived 

 with great force, we must give a short account of it in 

 its various forms. The phrase can be interpreted in a 



47 



