1891.] on Infectious Diseases. 291 



exerted by one microbe on tlie other : this practically means that the 

 products of one microbe either prevent the growth of another microbe 

 or neutralise its toxic action. It is perfectly well established that 

 while the products of one microbe exert an inimical action, when 

 present in sufficient amount, on the growth and life of the same 

 microbe (the protective inoculation by chemical products of tbe Bac- 

 teria cited above), the accumulation of the products of the particular 

 microbe interferes with, and eventually altogether stops the further 

 growth of its microbe. Outside the body this is easily proved in 

 artificial cultivations. Inside the body it is proved by those cases 

 in which recovery takes place. 



It has been shown that while some pathogenic microbes can well 

 thrive side by side in the same culture, inside or outside the body, 

 there are others where the growth of one is antagonistic to the action 

 of the other : erysipelas and anthrax (v. Emmerich), swine erysipelas 

 and swine fever, anthrax and Bacillus pyocyaneus (Charrin), anthrax 

 and Staphylococcus aureus ; this is due to the fact that the chemical 

 products of one species inhibit or neutralise the other species. That 

 this antagonism is really of a chemical nature is shown in the case of 

 anthrax and Bacillus pyocyaneus ; if the chemical products of this 

 latter microbe be injected into the animal simultaneously or soon 

 after inoculation with the anthrax bacilli, no anthrax disease ensues, 

 the anthrax bacilli do not multiply and do not produce the disease. 

 Apart from specific antiseptics, there exist, then, in the battle against 

 the action of pathogenic microbes which have already entered the 

 system of an animal, the following means : (1) the chemical antago- 

 nism offered by the healthy tissues themselves — in some cases this 

 is nought, in others very great and powerful, alterable by various 

 conditions; (2) the germicidal action of the blood and tissue juices of 

 unsusceptible animals on the multiplication of pathogenic Bacteria 

 within a susceptible animal ; (3) the antagonism existing between 

 the Bacteria and their own chemical products ; (4) the antagonism 

 of one species and its chemical products against another species. 

 These principles have, then, to be borne in mind as indicating the 

 ways in which the microbes can be prevented from producing 

 eventually the disease in a body into which they have found access. 

 Pagtenr's hydrophobia inoculations, .and many of the recently pub- 

 lished results of curative inoculations against tetanus, against anthrax, 

 and against diphtheria, are illustrations of these principles. 



The principle on which Koch's antituberculous lymph acts is 

 apparently of a different nature. Koch has found by experiment on 

 guinea-pigs that if the chemical products or an extract of the sub- 

 stance of the tubercle bacilli be injected into a body affected with 

 tuberculosis, the tubercular tissue becomes necrotic, while the 

 tubercle bacilli themselves remain unaffected ; at the same time a 

 remarkable reactive inflammation sets in, by which the necrotic 

 tissue becomes eliminated, either spontaneously, e. g. where the 

 tubercular process is superficial, as in lupus of the skin, or it may be 



