INFECTION, IMMUNITY, AND RECOVERY. 127 
protective substances, are always present in the body, 
and that under special need, as when bacterial inva- 
sion takes place, they are thrown out by the cells in 
larger quantities, and this is especially true of the 
special substances needed for existing infection. The 
antitoxin then acts by fortifying the cells so that they 
are enabled to resist the action of the toxin. In favor 
of this view is the fact that the cells of certain ani- 
‘mals are undoubtedly proof against these toxins, and 
yet so far as chemistry in its present development can 
detect, these cells are the same as similar but sensitive 
cells in other animals. Another theory is that the 
toxin, in some way in the body fluids, is changed into 
antitoxin. This is made slightly plausible by the fact 
that by the action of electricity there have been obtained 
substances from toxins which are slightly antitoxic. 
The practical point to remember is that whether or not 
the thevries are correct, there is no doubt that the pro- 
tective substances exist. 
