254 Veterinary Medicine. 



bacillus anthracis, amounting in some cases to virtual immunity, 

 and in others having very little effect. The object in immu- 

 nizing is to stimulate to the encrease of these defensive products 

 in quantity or power until an ordinary dose of the bacillus will 

 fail to colonize the tissues or the blood. In considering this sub- 

 ject a clear distinction must be made between the simple bacteri- 

 cidal and the antidotal or antitoxic products found in the serum 

 of immune animals, and the toxins which are produced by the 

 bacilli. The soluble antitoxic and bactericidal agents found in 

 the serum of the immune, may be employed for therapeutic pur- 

 poses to preserve life in an animal which has received a lethal 

 dose of the bacillus anthracis, but, as these are rapidly eliminated 

 from the system, their protective power is very short-lived, and 

 if some bacilli survive the period of their presence and potency, 

 or if the bacilli are introduced into the system later, the animal 

 may fall a victim to anthrax as if no such protective agent had 

 been used. Behring showed that the blood-serum of the white 

 rat proves fatal to the bacillus anthracis, but MetchnikofI pointed 

 out later that it must be brought in contact with the bacillus in 

 order to prove effective, whereas if the serum and bacillus were 

 injected at different parts of the body no protection was obtained. 

 The antidotal or bactericidal action of the serum of an immu- 

 nized animal acts at once, whereas a permanent immunity cannot 

 be established before about fifteen days. The serum of the im- 

 mune animal contains the following elements antagonistic to an- 

 thrax : Antitoxin or leucomain, which may be poisonous to the 

 bacilli, or chemical antidotes to their products : globulicidal prin- 

 ciples which distort or disintegrate the blood globules and release 

 their contents, including the bactericidal nucleins : precipitins, 

 agglutinins, etc. All such agents, when injected into the sys- 

 tem, are present only for'a limited time, and while they may be 

 subservient to a temporary immunity, they can give no perma- 

 nent protection and must be considered mainly as therapeutic 

 agents. 



A permanent immunity must depend on a stimulation of the 

 system to the production of these defensive agents de novo or in 

 encreased quantity. This must be done by exposure of the 

 tissues to the toxins of the bacillus anthracis, and is accomplished 

 slowly. All the tissues that engage in the production of the de- 



