428 ACTINOMYCETES. 



Mycobacteria which Grow Luxuriantly at Room Tem- 

 perature. 



Literature. — The real discoverer of these organisms in butter is Petri. 

 He pointed them out to R. Koch in July, 1896, who expressed his 

 belief that they were different from true tubercle bacilli, which was 

 also the opinion of Petri. A subsequently undertaken investigation 

 by Lydia Rabinowitsch at Koch's suggestion appeared before Petri's 

 work as a preliminary communication in the Deutsch. med. Wochen- 

 schr., Aug. 5, 1897, and in detail in Z. H. xxvi, 1897, 90. Petri's 

 work was published (A. G. A. xiv, 1, 1898) after he had published a 

 note concerning it in the H. R. , Aug. 15, 1897. 



Further important communications are : Hormann and Morgenroth 

 (H. R., 1898, 217 and 1081); Moeller (Verh. d. Gesell. deut. Naturf. u. 

 Aerzte, 1898 ; Deutsche med. Wochenschr., 1898 ; andC. B. xxv, 369); 

 O. Schultze and Lubarsch (Z. H. xxxi, 153). 



The most interesting discovery in the field of the mor- 

 phology of bacteria during the past three years is to be 

 considered that of the micro-organisms resembling the 

 tubercle bacillus. Three years ago every acid-proof bac- 

 terium was a " tubercle or lepra bacillus"; to-day we 

 know, through the harmonizing labors of many investi- 

 gators 1 (Petri, Rabinowitsch, Moeller, and others) that 

 acid-proof varieties occur not infrequently in the environs 

 of men and domestic animals. Still, their differential diag- 

 nosis from the Mycobacterium tuberculosis appears quite 

 easy, and yet the forms now known approach it in so 

 many characteristics that, after the experiences with diph- 

 theria and cholera, we must expect that still further diffi- 

 culties will arise after more extensive studies. The exceed- 

 ingly interesting forma piscicola of the Mycob. tuberculosis 

 described on page 420 shows us to what a degree the true 

 T. B. culture may change biologically (growth at room 

 temperature, formation of a violet pigment in milk). 

 Who knows how our newly discovered mycobacteria cul- 

 tures may change if they are cultivated at incubator tem- 

 perature or in the animal body for many generations ? 



To-day naturally it is not possible to consider the Myc. 

 tuberculosis, without further knowledge, as a form of one 

 of these organisms, which has been adapted to warm- 



1 In manure acid-proof bacteria had already been found by stain- 

 ing : Severin (C. B. L. I, 98) ; Ferran (C. B. xxn) ; Capaldi (Z. H. 

 xxvi, 105). 



