254 PATHOGENIC BACTERIA. 



researches of J. H. Wright l are in accord with those of 

 Tedeschi rather than with those of Baumgarten, for 

 Wright observed first a marked degenerative effect upon 

 the tissue, and then an inflammatory exudation amount- 

 ing in some cases to actual suppuration. 



As has been mentioned, cultures of the bacillus lose 

 their virulence more or less after four or five generations 

 in artificial media. While this is true, attempts to atten- 

 uate fresh cultures by heat, etc. have so far failed. 



Leo has pointed out that white rats, which are immune 

 to the disease, may be made susceptible by feeding with 

 phloridzin and causing a glycosuria. 



Kalning, Preusse, Pearson, and others have pre- 

 pared a substance, "mallein," from cultures of the 

 bacillus, and suggested its employment for diagnostic 

 purposes. It seems to be quite useful in veterinary 

 medicine, the reaction occasioned by its injection being 

 similar to that caused by the injection of tuberculin in 

 tuberculous patients. The manufacture of mallein is 

 not attended with great difficulty. The bacilli are grown 

 in glycerin bouillon for several weeks, killed by heat, the 

 culture filtered through porcelain and evaporated to one- 

 tenth of its volume. It has also been prepared from 

 potato cultures, which are said to produce a stronger 

 toxin. A febrile reaction of more than 1.5 C. following 

 the injection is said to be specific of the disease. Babes 

 has asserted that the injection of this toxic product into 

 susceptible animals will protect them from the disease. 



Various experiments have been made with curative 

 objects in view. Certain observers claim to have seen 

 good results follow the injection of mallein in repeated 

 small doses. Others, as Chenot and Picq, find the blood- 

 serum from immune animals like the ox to be curative 

 when injected into infected guinea-pigs. 



1 Jour, of Exp. Med. t vol. i., No. 4, p. 577. 



