BACILLUS MALLEI 533 



temperatures of 120 C. and prolonged storage without noticeable loss of 

 strength. 1 



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 aqueous and 

 glycerin extracts of potato cultures. Roux 2 cultivates virulent gland- 

 ers 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 min- 

 utes, 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. Concen- 

 tration 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 prepared 

 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 in- 

 tensely 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, and the local reaction is much smaller and more 

 transient. Injections are best made into the breast or the side of the 

 neck. 



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



2 Roux ct Nocard. Bull. d. 1. soc. centr. vet., 1892 



