ECONOMIC IMPORTANCE OF FUNGI 315 
of some animal that has had the given disease. As in the 
case of the preparation of vaccine, the animal is first placed 
in quarantine, under the most perfect sanitary surround- 
ings ; if found free from all contagious diseases, and other- 
wise satisfactory, he is given increasingly large doses of 
the toxin or the virus that causes the given malady. 
This treatment may require as long as six weeks, and re- 
sults in the formation of quantities of the antitoxin in 
the blood. A quantity of blood is then drawn from the 
animal, and the blood-serum isolated, filtered, carefully 
tested for purity, content of antitoxin, and freedom from 
disease-germs, and finally put up in glass syringe containers 
ready for use. When a person is exposed to the given 
disease (e.g., diphtheria), or has actually contracted it, 
the serum is injected into his circulatory system, where the 
antitoxin counteracts the toxin of the disease. The 
patient is thus rendered passively 1 immune. Serum- 
therapy is now successfully employed in the treatment of 
diphtheria, tetanus (lockjaw), hog cholera, and, with 
more or less success, of infantile paralysis and certain 
other diseases. 
Nothing corresponding to vaccination and serum therapy 
is known for a certainty in the" treatment of plant diseases. 
7. Antiseptic surgery. The greatest obstacle to suc- 
cessful surgery has always been the presence of the rich 
and varied microscopic flora, or plant life, in the air. 
When a wound was opened or a cut made the germs com- 
posing this flora found on the cut surface the most favor- 
able conditions for their growth and multiplication, and 
the poisons they secreted interfered with the healing of 
1 Passively, because the antitoxin is not produced by the activity of his 
own cells, as it is in the case of vaccination. 
