274 BACILLUS OF TETANUS 



be estimated quantitatively by ascertaining the minimum fatal dose 

 of a filtrate containing the tetanus toxin. It must be understood, 

 however, that the toxin is very unstable in the watery solution 

 represented by the filtrate; it soon loses in intensity, and is easily 

 damaged by heat and chemicals and antiseptics. The exposure of 

 a filtrate containing tetanus toxin to a temperature of 65 C. for five 

 minutes or of 60 C. for twenty minutes will almost completely 

 destroy the toxin. Electric currents passing through a filtrate will 

 destroy the toxin in a few hours. Mineral acids and alkalies destroy 

 it even in very weak concentration; organic acids require stronger 

 concentration. The poison can easily be attenuated by the addition 

 of certain antiseptics. Iodide trichloride (IC1 3 ), if present to the 

 slight degree of one one-hundredth per cent, will in one hour greatly 

 attenuate the toxin. 



Action of the Toxin upon the Nervous System. The effect of the 

 tetanus toxin upon the animal body is not yet well understood. It is, 

 however, very probable that the poison acts upon the central nervous 

 system by uniting with the cellular elements forming it, and, further, 

 that the toxin travels from its first place of deposit in the connective 

 or intramuscular tissue along the axis cylinders of the peripheral 

 nerves toward the central nervous system. Wassermann has shown 

 that if tetanus toxin is mixed with ground-up guinea-pig's brain the 

 toxin becomes united with the brain substance, making it evident 

 that an affinity exists which binds the tetanus toxin to the tissue of 

 the central nervous system. 



Component Bodies. Tetanus toxin, as it is present in the filtrate, 

 is composed of two bodies, tetanospasmin, a substance which has an 

 affinity for and which affects the central nervous system and causes 

 the convulsions, and tetanolysin, which has the property of dissolving 

 red blood corpuscles. 



Antitoxin Formation. When tetanus toxin is injected into an animal 

 an antitoxin is produced. The exact location where the latter is 

 formed, whether in the central nervous system or not, is unknown; 

 but the antitoxin is contained in the blood serum, and it can be 

 obtained by allowing the blood to coagulate so that the serum can 

 be separated from the clot or coagulum. Tetanus antitoxin is manu- 

 factured in the blood serum of the horse. The general principles 

 and steps in forming and procuring it are as follows : 



1. Inoculate a veal bouillon, containing 1 per cent, peptone and 

 0.5 per cent, sodium chloride, neutralized with carbonate of mag- 

 nesium, and then slightly acidulated with 0.1 per cent, lactic acid 

 from a pure culture of tetanus bacilli. Keep under strictly anaerobic 

 conditions in the incubator for ten or more days. 



2. Filter through an unglazed porcelain filter (Pasteur-Chamber- 

 land). 



3. Ascertain the minimum dose which will kill a mouse of about 

 10 grams within four days. 



