DESCRIPTION OF SPECIES. 



o2'6 



Fig. 206. — Puke-cultuee op Bacillus 

 Megatherium in Gelatine. 



Bacillus membranaceus ame- 

 thystinus (Eisenberg). — Short rods 

 with rounded ends from 1 to 1'4 /x 

 long, and -5 to -8 fi broad. They 

 are grouped together irregularly. 

 Some individual bacilli stain more 

 deeply at the ends than in the 

 middle. Non-motile. They grow 

 only between 15° and 20° C. Spore- 

 formation uncertain. 



The colonies gradually assume a 

 violet hue, and after liquefying the 

 gelatine float on the surface as violet 

 pellicles, resembling a membrane 

 stained with gentian violet. 



Inoculated in the depth of 

 gelatine a yellowish-white growth 

 appears on the free surface, which 

 after ten days or more becomes 

 violet. liiquefaction takes place 

 gradually, and in about a month 

 a thick violet layer covers the gela- 

 tine which lies beneath the liquid 

 part. 



On agar the growth, which at first 

 has a yellowish milky appearance, 

 becomes violet after eight or ten 

 days. In three or four weeks it 

 has become very much wrinkled, 

 and has a beautiful deep-violet 

 colour with a metallic lustre. The 



jelly is not stained, and the growth 

 can be easily removed from its 

 surface. 



On potato they grow slowly, and 

 form a dirty yellow or olive-green 

 colour. 



In broth they grow very slowly ; 

 after some weeks a violet deposit 

 and pellicle are formed, and the 

 liquid between becomes dark brown. 



They were found in well water. 



Bacillus meningitidis puru- 

 lentae (Neumann and Schaffer). — 

 Rods 2 /i in length, -6 to •? jj. in 

 width, and filaments. 



Colonies granular, greyish. 



In the depth of gelatine a greyish- 

 yellow filament develops, composed 

 of closely packed colonies, and on 

 the surface a greyish layer. 



On potato the growth is moist 

 and white. 



They are pyogenic in small ani- 

 mals and dogs. 



They were isolated from a case 

 of purulent meningitis. 



Bacillus mesentericus fuscus 

 (Flilgge). — Rods small and short, 

 singly, in chains of two and four. 

 Actively motile. Spore-formation 

 present. 



Colonies are at first roundish and 

 rather white, with a sharp outline ; 

 later delicate brownish-3-ellow pro- 

 cesses appear. Liquefaction occurs 

 rapidly. 



Inoculated in the depth of gela- 

 tine a whitish growth forms along 

 the track of the needle, the upper 

 portion of which soon liquefies ; 

 greyish flakes float in the liquefied 

 portion. 



On potato a smooth yellowish 

 growth appears on the first day, 

 but it soon becomes brown and 

 wrinkled. It remains relatively 

 thin and superficial, and quickly 

 spreads over the whole .surface. 



They are found in haj' dust, in 

 the air, on the surface of potatoes, 

 and are very widely distributed. 



Bacillus mesentericus ruber. — 

 Slender rods, singly, in pairs, and 

 in filaments. 



Colonies are circular and yellow- 

 ish until they come to the surface, 

 when they produce a network and 



