FORMATION OF DEFENSIVE FERMENTS /I 



very much diluted, and then probably pass straight 

 into the lymph, and possibly also into the cells of 

 the body. The optical method is not so exact as to 

 permit us to establish very minute changes in 

 rotation, and, even if it were possible to observe such 

 rotations, it would be impossible to know for certain 

 whether the fluctuations were not within the limits 

 of errors of observation. Moreover, the decom- 

 position undoubtedly proceeds quickly, so much so 

 that we are really indebted to a lucky chance \vhen 

 we are able to follow up the decomposition of the 

 injected matter in the plasma itself. These are 

 the reasons why we have to prove the presence of the 

 ferments by means of substrates, against which the 

 respective ferments are directed. The substrate is 

 the reactive for its corresponding ferment, and the 

 decomposition of the former betrays the presence of 

 the latter. 



It may be remarked that the clear establishment 

 of the presence of proteo- and peptolytic ferments in 

 the blood plasma, after injection into the circulation 

 of albuminous substances that are out of harmony 

 with the body, has supplied a real explanation of the 

 behaviour of parenterally injected proteins during 

 metabolism. There is no longer any doubt that 

 they are made use of, that is, that they are utilized 

 in the metabolism of the cells of the body, so far 

 as experience has shown decomposition to be 



