NATURAL RESISTANCE TO DISEASE—FLEXNER. 130 
bath, the injection into the circulation of a number of simple chemical 
substances—peptone, albumose, nucleinic acid, spermin, pilocarpine— 
are all followed under physiological conditions by hyperleucocytosis 
and by a temporary state of increased resistance to bacterial invasion. 
Moreover, in certain experimental infections, at least, there can thus 
be aroused a heightened power to overcome established infections— 
those caused, for example, by the cholera, meningitis, and pneu- 
mococcus germs. Perhaps the most striking example of the protect- 
ive influence of hyperleucocytosis is afforded by the experimental 
infection described under the name of cholera peritonitis of the guinea 
pig. Ifa fatal quantity of cholera germs be injected into the peri- 
toneal cavity of a guinea pig, symptoms of poisoning quickly set in 
and death results in a few hours. <A study of the conditions present 
in the peritoneal cavity shows that the bacteria have developed freely, 
that some have been broken up and disintegrated, and that very few 
preserved phagocytes can be found. Examination of the blood re- 
veals that the number of leucocytes in the general circulation has been 
reduced; and all the evidences point to the conclusion that not only 
has phagocytisis not taken place, but that there has been a general 
destruction of leucocytes produced by the cholera poison. If, how- 
ever, there be introduced into the peritoneal cavity of a guinea pig 
twelve to twenty-four hours prior to the inoculation of the cholera 
bacilli, a small amount of sterile salt solution, or bouillon, or one of 
the other chemicals mentioned, which procedure will bring into the 
peritoneum a considerable number of leucocytes at the same time that 
it causes a rise of leucocytes in the circulating blood, then the cholera 
germs are quickly taken up by the phagocytes, multiplication is pre- 
vented, and the animal escapes severe illness. 
The value of hyperleucocytosis as a defensive measure against in- 
fection must, probably, always remain greater than its value as a 
cure for established infection. ‘There are several reasons that make 
this conclusion probable—the capacity of the blood is increased in 
the direction of destroying bacteria without being augmented at 
the same time in the direction of neutralizing bacterial poisons; the 
organism that is already severely poisoned by infection reacts less 
certainly to the chemical agents that provoke hyperleucocytosis than 
the uninfected organism. And yet we may see the operation of the 
benign influence of hyperleucocytosis, associated with an increased 
passage of alexin-containing lymph through the vessels, upon certain 
local infections at least, in the results of measures that determine an 
augmented supply of blood to a diseased part; in the mechanical 
hyperemias produced through posture or superheated air; the in- 
fluence (in part) of tuberculin injections; and the effects of poultices 
and embrocations, of counterirritants, and of certain of the phe- 
nomena of local inflammation, 
