624 INFECTION AND IMMUNITY, 



complete recovery from the chronic form of the dis- 

 ease is infrequent. Something less than 50 per 

 cent, of the chronic infections in man terminate 

 in recovery. 



Bacillus The specific microbe, Bacillus mallei, discovered 

 in 1882 by Loeffler and Schiitz, is an aerobic or- 

 ganism which has approximately the morphology 

 and size of the tubercle bacillus, but lacks the acid- 

 fast property of the latter. It stains with anilin 

 dyes, especially carbol fuchsia, but not by Gram's 

 method. With weak staining it shows a granular 

 structure. It grows well on ordinary culture media, 

 showing a characteristic appearance on potato. In 

 unfavorable media it may produce threads, while 

 under more favorable conditions coccus-like forms 

 are seen. Marked involution forms occur on media 

 containing 3 per cent, of sodium chlorid 

 (Wherry) . The optimum temperature for growth 

 is from 30 to 40 C. 



Resistance The bacillus is only moderately susceptible to 

 toxin, sunlight, by which it is killed in about twenty-four 

 hours. It withstands freezing, lives for two or 

 three weeks in a dried condition at room tempera- 

 ture, and is killed by a temperature of from 56 to 

 60 C. in from ten minutes to one and one-half 

 hours, depending on the amount and character of 

 the medium in which it lies. Its resistance to the 

 ordinary disinfectants (corrosive sublimate, car- 

 bolic acid, etc.), is not high. Milk of lime and 

 solutions of calcium chlorid are suitable for the dis- 

 infection of stalls. In culture media the organism 

 secretes no soluble toxin, but it contains an endo- 

 toxin which probably is one of the constituents in 

 the various preparations of mallein. 



