BACILLI 475 



BACILLUS DENTEITICUS 



I LIQUEFIES G ELATINE | 



AutKority. — Bordoni-Uffreduzzi, Precis d^ Analyse microbiologique des 

 Eaux, G. Roux, 1892, p. 312. Also Diagnostik der Bahterien des Wassers, 

 Lustig, 1893, p. 99. 



Where Found.— In drinking water supplied to Turin. 



Microscopic Appearance. — A short bacillus with rounded ends, forms. 

 zoogloea masses in young cultivations made up of eight to thirty and even more 

 individual bacilli. It is 0*85 to 2*08 fi long and 0*50 to 0*85 fi broad. Capable 

 of lively oscillatory movement on its own axis. No spores are produced. 

 Stains best with aqueous alcoholic solutions of gentian and fuchsin. 



Cultures. — 



Gelatine Plates. — From a slightly raised central point eight or ten branches 

 from 2 to 3 mm. broad extend, which soon divide up into other branches, and so 

 on until they give rise to a colony which in shape resembles a tree agate. The 

 whole is shining, moist, and of a whitish colour, but is more distinctly so in 

 the centre and other parts of the colony where the growth is thickest. The 

 substance of the colony is slightly viscid, which is apparent on touching it 

 with a needle. In old cultures (forty to sixty days) the gelatine becomes soft- 

 ened in the middle of the colony, and gradually the whole becomes liquefied. 



Gelatine Tubes. — On the surface there appears a raised circular moist 

 white growth with a sharp contour, whilst in the depth appear numerous round 

 whitish colonies which are confluent. After some time the gelatine becomes 

 soft, and is finally liquefied, 



Agab-agar Plates. — When preserved at 22° C. there appears a thin dirty 

 white expansion, starting from a central point and spreading out with an ir- 

 regularly serrated edge. No growth takes place at 37*^ C. 



Agar-agar Tubes. — At 22° C. it grows much in the same way as on gelatine, 

 but at 37° C. an abundant development takes place in the depth, whilst a fine 

 almost invisible growth appears on the surface. 



Blood Serum. — Hardly any growth at 37° C. At 22° C. it develops more 

 abundantly in the depth than on the surface. After five to six days, however, a 

 smooth white expansion with a delicately serrated edge forms. In old cultures 

 the serum is liquefied. 



Broth. — At 22° C. it renders it turbid, and forms a white pellicle with a, 

 rough moist surface. This becomes so firmly attached to the walls of the tube 

 that the latter can be turned upside down without spilling the contents. At 

 37° C. it becomes slightly turbid and no pellicle is formed. In glycerine broth 

 at 37° C. a pellicle is formed, but it is less tough and always sinks to the bottom 

 of the tube. 



Potatoes, — At 22° C. produces a thick white moist and shining expansion 

 which spreads over nearly the whole surface of the potato. In old cultures the 

 growth becomes yellow. At 37° C. the growth is more restricted. 



