54 METHODS FOR THE STUDY OF FERMENTS 



that act on fats, carbohydrates, nucleo-proteids, 

 nucleic-acids, phosphatides, and so on. Everything 

 points to the fact that the cell has agents at its dis- 

 posal which render it capable of splitting up, into 

 their simplest units, all the complicated substances 

 which are brought to it, or which it itself builds up. 

 In favour of such a view, we may more particularly 

 cite, besides the direct proof of the existence of 

 ferments, the observation that in the metabolism of 

 the cell all the units, out of which the complicated 

 nutritive substances and the components of the cells 

 are built up, are found to occur. 



At the present time there is no doubt that an 

 important part of the metabolic processes of the cells 

 is furthered by ferments. In general, we may say 

 that complicated substances are hydrolytically reduced 

 in stages until the simplest structural units are 

 formed. Once the latter appear, then the further 

 reduction continues in stages, through various inter- 

 mediate products, right down to the end-products of 

 metabolism, or else the resulting products of decom- 

 position form the starting-point for new .syntheses. 

 From these products very varied links are forged 

 between very different groups of substances. 



It is thus proved that, in a certain sense, each 

 separate cell of the body is capable of digestion. This 

 holds particularly for the white and red blood cor- 

 puscles ; even the platelets are able to produce hydro- 



