THE PHENOMENA OF INFECTION 441 



The bacilli in the throat are not destroyed by natural 

 recovery or by cure with antitoxin, but the action of the 

 toxin is prevented by the antibody. It is not, in our opinion, 

 the toxin itself which kills, but a cleavage product which 

 results from the action of the toxin on the proteins of the 

 body. 



All ferments are of cellular origin. This does not mean 

 that ultramicroscopic forms of life or non-particulate living 

 organisms, if there be such, do not produce ferments. It 

 would probably be better to say that all ferments are the 

 products of living organisms and that there can be no living 

 organism which does not produce its specific ferment. 

 We cannot conceive of life without ferment action, because 

 all living things must feed and food assimilation without 

 ferment action is inconceivable. Food must be fitted for 

 assimilation, and this is dependent upon ferment action. 



Ferments are intra- and extracellular. All are formed 

 within the cell, but some diffuse into the medium while 

 others do not. In some instances at least cell permeation 

 by the pabulum is essential to the feeding of the cell. In 

 other instances it is highly probable that the ferment is 

 accumulated on the cell surface and there acts upon the 

 pabulum. In still other instances the ferment diffuses 

 into the medium more or less widely from the cell which 

 elaborates it. Many cells produce both intra- and extra- 

 cellular ferments, and these are not necessarily the same. 

 In some instances, probably in most cells, the intracellular 

 ferment cannot be extracted from the cell or obtained in 

 soluble form without destruction of the cell. This does 

 not mean that it must exist in the soluble form before it 

 can manifest its cleavage action. The pabulum may per- 

 meate the cell and in this location be split up by the intra- 

 cellular ferment. We have insisted upon this as an explana- 

 tion of the well-established fact that soluble proteins 

 sensitize muclrmore readily and completely than insoluble 

 ones. 



It will be well to illustrate what we have said about 

 cellular ferments by a condensed sketch of the work that 



