214 PHARMACEUTICAL BACTERIOLOGY 



n. Of equal amounts of enzyme isolated, on the one hand, and left in 

 their natural environment, on the other hand, the latter are by far more 

 active. Just why this should be is not clearly understood; the fact re- 

 mains that the enzymic product of manufacture is very frequently quite 

 inactive. No doubt the methods of manufacture have a destructive 

 influence upon the enzymes, or it may be that we have not yet learned how 

 to isolate the enzyme properly. Our knowledge of the action of the pro- 

 ferment of pepsin makes it clear that the present methods of manufactur- 

 ing pepsin are defective in principle. The full strength of active pepsin is 

 found in the stomach secretion, but not in the stomach extract or pepsin 

 of the market. 



The earliest students of ferments and of fermentation noted certain 

 analogies between the actions of chemicals and metals in certain states or 

 conditions, and ferments, and it is these analogies which started the con- 

 troversy as to whether the enzymatic processes were purely chemical, or 

 due to organic activity. The essential condition of the process of fermen- 

 tation is that the catalyzing or enzymatic agent shall not appear in the 

 end products of fermentation and that it shall remain unchanged chemi- 

 cally. In the usual generation of O, heat is applied to potassium chlorate 

 mixed with MnO2 resulting in the conversion of the chlorate into the 

 chloride with liberation of O. In this process the MnO2 remains chemi- 

 cally unchanged, simulating the action of a ferment in that it hastens or 

 accentuates (aided by the heat) the catalyzing process, and does not appear 

 in the end products. 



Again, it is known that metals, as platinum or silver, in a finely divided 

 state, will hasten catalytic processes. This is also true of certain metals 

 (gold, platinum, silver, copper, etc.) in the colloidal state, designated as 

 metallic sols. The colloids or sols are prepared by placing the metallic 

 electrodes (of the metals names) into pure water and passing an electric 

 current through them. If the water is not pure, or if it is allowed to 

 become heated, the metal is deposited or suspended as a cloud, and does not 

 form a true colloidal solution. The suspended and finely divided metal 

 particles can be filtered off, leaving the true metallic colloidal solution. 

 Sols thus prepared have the power of hastening catalytic processes with- 

 out themselves undergoing any chemical change. According to Fischer, 

 platinum sol will decompose (catalyze) hydrogen peroxide with only 

 JlJOOjOOO milligram of platinum in ice. of water. Metallic sols further 

 resemble true enzymes in that their catalytic action is readily inhibited 

 by a rise in temperature and also in that they are quite sensitive to the 

 actions of toxic agents, as arsenic, strychnine, etc. Fischer suggests that 

 the decomposition of true ferments by heat is merely a physical change 

 and that all ferments are perhaps colloidal solutions and in consequence 



