ECONOMIC IMPORTANCE OF FUNGI 315 



of some animal that has been rendered immune to the 

 disease. As in the case of the preparation of vaccine, the 

 animal is first placed in quarantine, under the most perfect 

 sanitary surroundings; if found free from all contagious 

 diseases, and otherwise satisfactory, he is given increas- 

 ingly large doses of the toxin or the virus that causes the 

 given malady. This treatment may require as long as 

 six weeks, and results 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 free- 

 dom 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 (lock- 

 jaw), 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. 



