ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 345 



bacillus have been obtained, but from injections of material containing 

 enormous numbers of the bacilli, it appears to be non-pathogenic. 



The well-known bacillus of avian tubercle is probably the B. tuber- 

 culosis modified by its environment, for the only essential difference it 

 presents is with regard to its pathogenicity : similarly it is highly pro- 

 bable that tuberculosis in cold-blooded animals is due to tubercle 

 bacillus modified somewhat by the conditions of its habitat. Lubarsch, 

 Dubard, and others, by means of passages through frogs and fish, have 

 succeeded in modifying the characteristics of the mammalian tubercle 

 bacillus to a marked extent, whilst Moeller himself, by passing it through 

 the slow-worm, effected such changes that the tubercle bacillus would 

 no longer grow at a higher temperature than 30° C, and this character 

 persisted even after subsequent passage through warm-blooded animals, 

 whilst the cultural appearances closely resembled those of the bacillus 

 of avian tubercle. 



Moeller also refers to other acid-fast bacilli, — the Petri-Rabinowitsch 

 butter bacillus, the Timothy grass bacillus (B. phlei), and the grass 

 bacillus ii., the dung bacillus, &c, all of which closely resemble the 

 tubercle bacillus in morphology (though individual rods may be some- 

 what thicker), and when injected into animals produce lesions which to 

 the naked eye simulate true tuberculosis. The author considers that 

 B. tuberculosis, like all acid-fast bacilli, belongs to the Streptotrichiae. 



Fat Substance of the Tubercle Bacillus.* — K. Kresling prefaces 

 a communication on the fat substance of the tubercle bacillus with a 

 short historical account of the work previously done on this subject. 



In his own investigations the tubercle bacillus was cultivated for 

 4 to 5 months at 37° C. in small broad-bottomed Erlenmeyer flasks, con- 

 taining 5 p.c. glycerin-broth. The medium when finished, reacted acid 



n 

 to phenolphthalein to the extent of 0*1 to 0*4 ccm. — NaOH per 



100 ccm. The resulting growth was killed in the autoclave at 110° C, 

 collected on filter paper, washed with hot distilled water to free it from 

 glycerin, &c, spread upon porous earthen plates, and finally dried at 

 about 40° C. The result was a yellowish spongy mass, which could 

 easily be pulverised, and which, if exposed to the air, took on a reddish 

 tinge. 



The result of Kresling's analyses may be summarised as follows: — 



(1) Composition of the Dried Tubercle Bacillus. Moisture (dried 

 at 100°-110° C), 3-9375 p.c. (after drying in the H 2 S0 4 desiccator, 

 3 '08 p.c); ash, 2*55 p.c. ; nitrogen, 8*575 p.c. ; nitrogenous substance, 

 — albumen — excluding the nitrogen of the lecithins, and other sub- 

 stances soluble in alcohol, ether, chloroform, and benzol, 53 "59 p.c; 

 fatty substances, 38*95 p.c; N-freo substances, 0*9725 p.c. 



(2) Fatty Substance obtained by extraction with CHCl 3 presented the 

 following characters : — Melting-point, 46° C. ; acidity, 23*08; saponi- 

 fication value, 60*70. And had the following composition: — Free fatty 

 acid, 14*38 p.c. ; neutral fat and residual fatty acids, 77*25 p.c. ; fatty 

 acids in general (with a melting-point of 53*5° C, not estimated; 

 leci thine, 0*16 p.c; cholestrin, not estimated; substances directly 



* Centralbl. Bakt., !*• Abt., xxx. (1901) pp. 897-909. 



