20 I.\THODUCT1<>\. 



as far removed from an adequate explanation of these phenomena 

 as in the beginning, 



Within recent years repeated observations have shown that from 

 various organs of the body certain substances ean be extracted which 

 arc apparently identical with or closely related to the so-called di- 

 xy mes. Certain representatives of this class, such as pepsin, trypsin, 

 ptyalin, and others, are, as \\e shall see, formed in the cells of the 

 digestive glands of the body, and serve the purpose of transforming 

 the various food-stuffs which are furnished the animal by the plant 

 into forms which can be absorbed and built up into its tissues. The 

 chemical processes which are here involved are essentially of the 

 character of hydrations. Other bodies, however, of this order 

 which can be obtained from living tissues, and which are also 

 capable of manifesting their special activity after the death of their 

 pa rent-cells, apparently possess the power of oxidation, and it is 

 hence supposed by some that these processes in the living tissues 

 may also be referable to such enzymotic activity. Whether this 

 is actually the case is not definitely known. But if so, we are 

 apparently approaching a time when what we have heretofore been 

 forced to ascribe to the activity of a special vital force may be 

 explained upon the basis of physical laws which are seen also at work 

 in the non-organized world. For we know 7 that properties which are 

 supposedly characteristic of the enzymes are possessed also by cer- 

 tain elements which are found only in the inorganic world. The 

 most notable properties of the enzymes are their ability to effect an 

 amount of chemical change which is out of all proportion to the 

 quantity of the enzyme present, and the fact that the enzyme itself 

 apparently does not enter into the reaction. These same properties, 

 however, are common to certain metals and their oxides. Bredig 

 and von Berneck showed that a gram-atomic weight (193 grams) of 

 colloidal platinum diffused through 70,000,000 liters of water shows 

 a perceptible action on more than 1,000,000 times the quantity of 

 hydrogen peroxide ; and H. C. Jones demonstrated that the reac- 

 tion which here takes place is a mono-molecular reaction, which 

 indicates that the platinum itself does not enter into the reac- 

 tion. Curiously enough, the analogy between the action of such 

 metallic solutions and that of the enzymes goes still further. Finely 

 divided platinum, palladium, iridium, osmium, etc., thus have the 

 power of inverting cane-sugar, like one of the enzymes, invertin ; 

 and certain poisons, such as hydrocyanic acid, sulphuretted hy- 

 drogen, carbon disulphide, and mercuric chloride, which inhibit or 

 even suspend the action of the enzymes entirely, exert a similar 

 influence upon a solution of colloidal platinum. Without entering 

 upon this very interesting subject further, it is clear that a path has 

 been opened upon which it may be possible to penetrate into the 

 my-teries of the so-called vital forces, and to show ultimately that 

 such forces are essentially the same as those met with in the non- 

 living world. 



