36 FUNDAMENTAL PROPERTIES 



Thus under certain conditions dilute sulphuric acid will change 

 starch into dextrine and sugar without undergoing any alteration 

 itself ; while finely divided platinum brought into contact with 

 oxygen and hydrogen will cause them to combine and form water. 



Later, it was ascertained that catalysis, or " contact action " as it 

 was termed by Mitscherlich, is also a property possessed by 

 the great class of soluble ferments known as 'enzymes,' which 

 play such an important part in fermentations and in very many of 

 the life-processes of organisms — these enzymes being complex 

 chemical products elaborated during the life of cells, in their own 

 substance, where they are sometimes retained and at others 

 excreted. The investigations of Verworn, Hoffmeister, Ostwald, 

 and others have shown what an important part the catalytic actions 

 of enzymes play in the metabolic processes carried on in the body 

 by cells of different kinds. Ostwald for instance in a discourse 

 "On Catalysis" delivered in 1901 at Hamburg said : — "We must 

 recognise the enzymes as catalysators that arise in the organism 

 during the life of the cells, and by their action relieve the living 

 being of the greater part of its duties. Not only are digestion and 

 assimilation controlled by enzymes from first to last, but the fun- 

 damental vital action of most organisms, the production of the 

 necessary chemical energy by combustion at the expense of the 

 oxygen in the air takes place with the explicit co-operation of 

 enzymes, and would be impossible without them." Verworn also 

 advocates the importance of catalysis in the work of assimilation, 

 as carried on by certain ultimate minute units of living matter 

 which he terms ' biogens,' and agrees with Ostwald in regarding the 

 processes that occur as essentially physico-chemical in nature.' 



So far we have been dealing with cases in which the simplest 

 living units avail themselves of materials — either inorganic or 

 organic — in a state of solution ; but in multitudes of other cases 

 solid food is taken which requires to be dissolved ('digested') 

 before it is assimilated. This happens for instance with all kinds 

 of Amoebae, with Ciliated Infusoria, with Sun Animalcules and 

 others. Where the food masses so taken are small they are 

 commonly received into small cavities or ' vacuoles ' in the body 

 substance of such organisms, and within such vacuoles they 

 gradually become dissolved, the products of solution ultimately 



' See his "General Physiology," 1899, Transln., pp. 481-6, and 529. This 

 subject is also fully discussed in the work of Reynolds Green on " Soluble 

 Ferments," 1899, Chap. XXIV. 



