502 PATHOGENIC MICROORGANISMS 



ated for man by passage through the turtle, although, as far as we are 

 aware, no definite statement as to this has been made. 



Summarizing the work of many investigators (Weber, Taute, 

 Kiister, Allegri, Eertarelli, and others) Ktister 1 makes a statement 

 which is, in essence, as follows: In the carp, in snakes, turtles, 

 and frogs spontaneous tuberculosis may occur. The organisms which 

 cause these diseases are specific for cold-blooded animals, similar in 

 many respects to the tubercle bacillus of warm-blooded animals, but 

 in the latter do not produce progressive disease. Human, bovine, and 

 avian tubercle bacilli inoculated into cold-blooded animals can produce 

 lesions which histologically simulate tuberculosis. These micro- 

 organisms can remain a year in cold-blooded animals without losing 

 their pathogenicity for guinea-pigs. Mutation of the tubercle bacillus 

 of warm-blooded animals into cold-blooded ones has not been proven. 



For these reasons it is quite impossible to exclude, in the apparently 

 positive work of Friedmann and others, the isolation of a true " cold- 

 blooded" type organism, rather than a mutation form originally of 

 the warm-blooded type. What Friedmann's present claims in this 

 respect are for his culture has not been stated as far as we know. The 

 possibility of a positive immunizing value of organisms isolated from 

 cold-blooded animals in human beings, though remote, is not out of ques- 

 tion. The problem is so serious and important, and the experience of 

 many workers is, so far, so inconclusive that the time has not come for 

 commercial exploitation and the cruel arousing of false hopes. The 

 subject, however, deserves carefully controlled further investigations. 



Bacillus of Timothy. Moeller isolated from timothy-grass and from 

 the dust in haylofts acid-fast bacilli, like Bacillus tuberculosis. They 

 grow rapidly on agar, soon showing a deep red or dark yellow color. 



Bacillus butyricus (Butter Bacillus). Slightly acid-fast bacilli re- 

 sembling Bacillus tuberculosis have been isolated from milk and butter 

 by Petri, 2 Rabinovitsch, 3 Korn, 4 and others. 



These bacilli are easily differentiated from Bacillus tuberculosis cul- 

 turally. They are slightly pathogenic for guinea-pigs, but not for man. 



Bacillus smegmatis and the bacillus of leprosy will be discussed in 

 separate sections. The differentiation of these organisms by staining 

 reactions has been discussed in the section on staining methods. 



1 Kolle und Wasscrmann's Handbuch, 2d edition, v, 767. 



2 Petri, Arb. a. d. kais. Gesundheitsamt, 1897. 



3 Rabinovitsch, Zeit. f . Hyg., 1897. 



4 Karn, Cent, f . Bakt., 1899. 



