792 PATHOGENIC MICROORGANISMS 



from many other bacterial poisons in being extremely resistant. It 

 withstands temperatures of 120 C. and prolonged storage without 

 noticeable loss of strength. 9 



In its physiological action upon healthy animals, mallein is not 

 a powerful poison. It can be given in considerable doses without 

 causing death. Mallein may be obtained by a variety of methods. 

 Helman and Kalning, the discoverers of this toxin, used filtered aque- 

 ous and glycerin extracts of potato cultures. Houx 10 cultivates 

 virulent glanders bacilli in flasks containing 250 c.c. each of 5 per 

 cent glycerin bouillon. Growth is allowed to continue at 35 C. 

 for one month. At the end of this time, the cultures are sterilized 

 at 100 for thirty minutes, and evaporated on a water bath to one- 

 tenth their original volume. They are then filtered through paper. 

 This concentrated poison is diluted ten times with 0.5 per cent 

 carbolic acid before use. Concentration is done merely for purposes 

 of conservation. The diagnostic dose of such mallein for a horse 

 is 0.25 c.c. of the undiluted fluid. 



At the Washington Bureau of Animal Industry, mallein is pre- 

 pared by growing the bacilli for five months at 37.5 C. in glycerin- 

 bouillon. This is then boiled for one hour and allowed to stand 

 in a cool place for one week. The supernatant fluid is then decanted 

 and filtered through clay filters by means of a vacuum pump. The 

 filtrate is evaporated to one-third its original volume on a water 

 bath, and the evaporated volume resupplied by a 1 per cent carbolic 

 acid solution containing about 10 per cent of glycerin. 



Diagnostic Use of Mallein. The injection of a proper dose of 

 mallein into a horse suffering from glanders is followed within six 

 to eight hours by a sharp rise of temperature, often reaching 104 

 to 106 F. (40 C. +). The high temperature continues for several 

 hours and then begins gradually to fall. The normal is not usually 

 regained for several days. Locally, at the point of injection, there 

 appears Within a few hours a firm, hot, diffuse swelling, which 

 gradually extends until it may cover areas of 20 to 30 centimeters 

 in diameter. The swelling is intensely tender during the first twenty- 

 four hours, and lasts for three to nine days. Together with this 

 there are marked symptoms of general intoxication. In normal 

 animals the rise of temperature following an injection is trifling, 



9 Wladimiroff, in Kraus und Levaditi, "Handbuch," etc., 1908. 

 ln Roux et Nocard, Bull. d. 1. soc. centr. v6t., 1892. 



