304 IMPORTANT VARIETIES OF FISSION-FUNGI. 



lively immunized animals possesses active bactericidal sub- 

 stances. In the place last referred to is also found an 

 extensive review of the literature. 



Bacterium of Brick=pock (Backsteinblattern). 

 Lorenz (C. B. xi, 672). 



A disease of swine, evidently to be considered as a form of swine 

 erysipelas, which almost always runs a favorable course, has been 

 described by Lorenz as brick -pock, and he has ascribed it to an organ- 

 ism which, upon subcutaneous inoculation, stands midway, as to viru- 

 lence for swine, between mouse septicemia and swine erysipelas. 

 After inoculation with it, swine become immune to swine erysipelas. 

 Rabbits, on the contrary, in a very interesting manner are much more 

 susceptible to brick-pock than to swine erysipelas. They always suc- 

 cumb to brick -pock infection, but may be immunized with swine 

 erysipelas against brick-pock. Lorenz likewise holds that swine ery- 

 sipelas, mouse septicemia, and brick -pock are produced by forms of one 

 organism, even if the transformation of one form into the other has 

 not been entirely successful. 



2. Bacillus F. Cohn, emend. Hiippe. 



Straight rods, often growing into threads, often of con- 

 siderable thickness, rarely less than 0.6, usually more 

 than 0. 8 p.. They form endospores. 



Key to the Recognition of the More Important 

 Varieties of the Genus l Bacillus. 2 



I. AEROBIC VARIETIES, thriving only scantily anaerobically. The 

 pathogenic ones never form spores in the animal body, but only in 

 cultures with oxygen admitted (compare also p. 310). Almost all in 

 cultures grow into long threads with central spores. 



1 Regarding our insufficient knowledge of this genus, consult the 

 statements upon page 306 and in the discussion of the anaerobes. 

 Numerous new aerobic varieties are described by Burchard (A. K. 

 II, 1). 



2 The genus Tyrothrix Duclaux is included in the bacilli. It 

 designates primarily varieties originating from milk and cheese, which 

 form spores and grow into long threads. Two species are described 

 below: Bac. tenuis and Bac. geniculatus. The most remarkable 

 statements of W. Winkler regarding extraordinary biologic and mor- 

 phologic variability, especially in the Bact. tenuis (C. B. L. I, 657), 

 could not be confirmed either by ourselves (see first edition) or by 



