SYSTEMATIC AND DESCRIPTIVE. 159 



composed of short segments. The rods are motile> 

 and form irregular chains, of a disjointed appear- 

 ance. Spore formation occurs in the usual way. 

 It was first observed on boiled cabbage, and thence 

 cultivated in a solution of grape-sugar and nutrient 

 gelatine. 



Bacillus Fitzianus, Zopf. Cocci, short rods, 

 long rods, and threads. This bacillus, cultivated 

 in meat extract and glycerine at 36 C., causes an 

 active fermentation with the production of ethyl 

 alcohol. Spore formation occurs in the rods. Ob- 

 served in unboiled hay infusion, accompanying the 

 hay bacillus. 



Bacillus tuberculosis, Koch.* Rods 2 4 ^ 

 and occasionally 8 p, long, very thin, and rounded 

 at the ends. They are straight or curved, and 

 frequently beaded, and occur singly, in pairs, or in 

 bundles. They are found in the cells of tubercles, 

 especially in the interior of giant cells. In the 

 latter they are often accompanied with grains which 

 exhibit the same colour reaction (Plate XVIII. , Fig. 

 i). They are non-motile. Spore formation occurs, 

 even within the animal body, the spores having the 

 appearance of clear vacuoles. The bacilli can be 

 cultivated artificially. The best medium is solid 

 blood serum (p. 81) of cow or sheep, with or without 

 the addition of gelatine ; and the most favourable 

 temperature for their development is 37 38C. The 



* Koch, BerL Klin. Woch., No. 15, 1882; and Mittheil. aus 

 dem Kaiser lich. Gesundheitsamte ; Aetiologie der Tuber kulose. 



