742 PATHOGENIC MICROORGANISMS 



In glucose Irotli there is general clouding and large quantities of 

 gas are formed. At 35 C. and over, the gas formation ceases after 

 four or five days, the broth becoming clear with a yellowish-white 

 flocculent sediment. At lower temperatures this does not occur. 



Milk is not coagulated and disaccharids and polysaccharids are not 

 fermented. 



The gas formed in cultures consists chiefly of hydrogen and 

 methane. All cultures have a sour odor, like butyric acid, but this 

 is not so offensive as that of some of the other anaerobic organisms. 



The bacillus lives longest in gelatin cultures, but even upon these, 

 transplantations should be done every four to six weeks, since the 

 spores of this bacillus show less viability and resistance than do 

 those of most spore-formers. 



Isolation. The isolation of B. botulinus from infected material 

 is often quite easy, since as Burke states, few other organisms may 

 be present in the canned or pickled food products. Often anaerobic 

 shake cultures in agar made directly, serve to isolate the organisms. 

 In most contaminated material, however, she recommends inoculation 

 from the original material into Von Ermengem's broth, inoculating 

 quite richly, duplicate cultures being made and heated at 60 for 

 one hour, to destroy non-spore bearers. These cultures are then 

 incubated at 28 after which parts of them are filtered, and the 

 filtrate in quantities of 1 c.c. injected into 250-gram guinea-pigs. 

 If the guinea-pigs die within four days, the pigs are again tested 

 with specific botulismus antitoxin. The presence of the organisms 

 having been thus proven in the broth, isolation is now carried 

 out by careful anaerobic plating or shake cultures. We do not know 

 whether the platinized asbestos method has been used in botulismus 

 work, but would recommend its use in cases, such as those men- 

 tioned. 



Botulismus Toxin. Botulismus toxin is produced under condi- 

 tions of strict anaerobiosis on any media on which the organism 

 will grow readily. According to Dickson 44 the toxin is much more 

 potent if the organisms are grown on an alkalin medium and in 

 the dark. Von Ermengem 45 obtained his best toxin by growing the 

 organisms on a beef infusion broth to which he added 1 per cent 



44 Dickson, Monograph of the Rock. Inst., No. 8, July 31, 1918, (la). Jour, of 

 the A. M. A., 65, 1915, 492. 



45 Von Ermengem, quoted from Kolle and Wassermann, Second Edition. 



