572 THE POPULAR SCIENCE MONTHLY 



Many substances burned in the body — sugar, for example — ^may 

 undergo slow oxidation in alkaline solution in the presence of atmos- 

 pheric oxygen (Og). In the body, however, it is burned at a faster 

 rate, leading to the conclusion that some other substance or substances 

 are necessary. The search for such substances has led to the discovery 

 of so called oxidizing enzymes, which oxidize many organic substances. 

 It is characteristic of an enzyme, however, that it accelerates but one 

 reaction. For the complete oxidation of grape sugar, for instance, it is 

 supposed that a series of enzymes is necessary. This must remain for 

 some time a supposition, as no pure substance or mixture of soluble 

 substances has been extracted from the body that will completely oxidize 

 grape sugar. 



It might be concluded that "life" is essential to such oxidations, 

 but such is not the case. In some instances ground up tissue, free 

 from entire cells, absorbs oxygen and gives out CO2 at a rapid rate. 

 It is evident that some substances are completely oxidized in the process. 

 The question has been raised as to whether the cell structure which has 

 not been completely destroyed in grinding the tissue be necessary for 

 the oxidation. In certain experiments Harden and McLean failed to 

 observe respiration in juice pressed out of muscles and other tissues. 

 Warburg and Meyerhof ground nucleated red-blood corpuscles with 

 sand, finding that the mass did not absorb oxygen or give out CO2, 

 whereas the original cells did. Warburg tried to destroy the structure 

 completely by grinding corpuscles in a steel box; with steel spheres 

 rotating at such high speed it was found necessary to cool the box with 

 ice in order to prevent injury to the corpuscles by heat (Barnard & 

 Hewlett apparatus). All microscopic structure was destroyed and res- 

 piration ceased. 



In other experiments, Warburg ground up liver cells, passing the 

 juice through a Berkefeld filter. The respiration of the juice was but 

 five per cent, of that of the corresponding amount of liver cells. But 

 when a coarser filter was used which allowed the passage of cell granules, 

 the oxidation was found to increase to twenty per cent, of that of 

 intact cells. 



If blood corpuscles be placed in water, or in certain solutions, the 

 hemoglobin passes out of them, they become pale and are called 

 "ghosts." This liberation of the hemoglobin, known as "laking," is 

 a kind of cytolysis. Warburg laked nucleated red-blood corpuscles of 

 a goose, finding that respiration continued in the " ghosts," but did not 

 occur in the fluid procured by laking. 



Such experiments seem to show that the presence of solid structures, 

 granules, etc., accelerates the respiration, since no substances were elimi- 

 nated in the process of grinding. It is possible that the solid structures 

 act in the same way, as does finely divided platinum (called platinum 



