488 
8. J. J. HAEGER. 
is thus reciprocally successful to combat microbes or their 
products, to which it owes at least indirectly its origin. 
Serum therapeutics was first studied in a crude way in 
cow-pox septicaemia in the dog, but has only attracted spe¬ 
cial attention since Behring and Kitasato have demonstrated 
the properties of the blood-serum of animals immunized against 
tetanus and diphtheria. They recognized in the blood-serum of 
such animals both preventive and curative properties when 
injected either before or after the introduction of disease 
germs into the body. 
Some anti-toxin blood serums have the power of counter¬ 
acting the virus of other diseases. Thus, the serum of animals 
immunized against symptomatic anthrax is effective against 
the bacillus of acute septicaemia (Duntschman). The serum 
of a healthy man, and at times that of the horse, is immunizing 
against the intraperitoneal injections of cholera (Pfeiffer). 
The prophylactic action of blood serum is therefore not abso¬ 
lutely specific; it is possessed in some instances by normal 
serum. 
Both the toxin and the anti-toxin are albuminous bodies, 
very similar in chemical properties but different in physio¬ 
logical action, and precipitates by alcohol, which permits of its 
preparation in a condensed form. 
Preparation of the Toxin —The process of preparing the 
toxin varies with the variety of the specific microbe. Suffice 
is to say that the latter is grown upon a favorable medium, such 
as bouillon, gelatine, agar, etc., the mature culture (diphtheria) 
being passed through a Chamberland filter; the filtrate, a 
clear liquid containing the toxin, is preserved in well filled 
corked bottles. It gradually loses its activity. 
Immunization of the Animal .—This may be accomplished 
by subcutaneous injections of small and repeated doses of pure 
or heated toxin; a better method, that of Roux and Villard, 
consists in mixing three parts of toxin with one of Gam’s solu¬ 
tion of iodine. The initial dose in the rabbit is one-half cc. 
(7 drops) repeated every three or four days for several weeks ; 
the dose is then gradually increased, and finally the undiluted 
toxin is given. The horse is the animal usually selected to* 
