ENZYMES »3 



which the heat and energy originate, and upon which life is so alarm- 

 ingly dependent — going on, not chiefly in the lungs or blood, but in 

 every cell of the body, is responsible to an enzyme, or catalase, known 

 as an oxidase. The result of these elements, which is the bringing 

 about of the union of oxygen with the tissue, is perfectly well known, 

 but the chemical nature and the physical characteristics of the oxidases, 

 are problems for speculation. 



The enzymes in plant cells are similar at least in action to the 

 corresponding ones of animals; but, in addition to those possessed by 

 animals, plants have ferments which enable them, in the sunlight, to 

 use carbonic acid gas in building up some of its cell constituents. 



The method used in the laboratory for demonstrating the presence 

 of an enzyme is very simple. The tissue to be examined is finely 

 minced and ground up in a mortar. In order to facilitate the divi- 

 sion of the cells, sand may be used in the grinding. The pulverized 

 mass is then mixed with water or a dilute salt solution, which dis- 

 solves the enzyme. To find out what the nature of the enzyme may be, 

 a small amount of the solution just prepared above, free of residue, is 

 added to a solution of a substance, as starch, fat, or proteid, which an 

 enzyme may decompose. After the course of a few hours the mixture 

 is "tested for the splitting products of the respective substance added. 

 If such be found and none were in either solution when kept separate, 

 it may be safely concluded that an enzyme has been discovered in the 

 tissues examined. Very likely it can be demonstrated that the tissue 

 contains more than one ferment, by showing that the tissue extract 

 will split more than one class of substances. 



It has been but recently discovered that enzymes or, better, pro- 

 enzymes have an interaction. The pure secretion from the pancreas 

 does not digest proteids. The unadulterated juices from the intestinal 

 wall do not split up proteids. But a mixture of the two secretions 

 possesses marked proteolytic powers. This phenomenon has also been 

 observed with other ferments. 



It has been known for years that certain finely divided metals, like 

 silver, platinum, gold and others, possess the property of accelerating 

 some of the reactions of, or chemical changes in, inorganic chemistry. 

 As an example — if any one of the above metals be added to a solution 

 of hydrogen dioxide, the compound is decomposed into its constituents, 

 water and oxygen. It remained, however, till recent years for a young 

 man working in the physiological laboratory of one of our great uni- 

 versities to show that these finely divided metals, elements of the 

 inorganic world, could perform the function of a body ferment. Finely 

 powdered platinum prepared by precipitation — known as platinum 

 black — when added to a simple fat, decomposes it, in the same manner 

 as a body enzyme would do. The metal has practically all the char- 



