26O BACTERIOLOGY. 



. Spirillum tyrogenum, Deneke. Curved rods, 

 slightly smaller than Koch's comma-bacilli, with 

 a great tendency to form long spirillar threads 

 .(Fig. 98). The colonies on plate-cultivations are 

 sharply defined, and of a greenish-brown colour. 

 After a time they liquefy the gelatine, but the 

 liquefaction is much more marked than in colonies 

 of Koch's commas of the same age, though not so 

 rapid as in the case of the commas of cholera 

 nostras. In test-tubes of nutrient gelatine a turbid 

 liquefaction occurs along the needle track, and on 

 the surface of nutrient agar-agar a yellowish-white 



FIG. 98. SPIRILLUM TYROGENUM. From a cultivation in nutrient 

 gelatine, X 1200. 



layer develops. Inoculation of potatoes gives no 

 result. Administration of the bacilli by the mouth, 

 in the manner employed for testing the pathogenic 

 effect of Koch's bacilli, produced a fatal result in 

 a few cases ; on the other hand, injection into the 

 duodenum failed entirely. The pathogenic proper- 

 ties may be, therefore, considered as not yet 

 established. They were isolated from old cheese. 

 Spirillum plicatile, Ehrenberg (Marsh-Spiro- 

 chcete).li\im threads, 2-25 //, in breadth, with 

 numerous narrow windings, 1 10 125 /itlong, occur- 

 ring also in spirulinar forms. The threads have 

 primary and secondary windings ; the former are 

 in each example of equal size, but the latter are often 



