522 



DESCRIPTION OF SPECIES. 



the track of the needle, and, the 

 whole of the gelatine gradually 

 becomes liquid, with a flocculent 

 deposit at the bottom and a greyish 

 wrinkled stain on the surface. 



Onpotato a thick wrinkled whitish 

 skin forms, which rapidly grows 

 over the whole surface. On at- 

 tempting to raise this skin it will 

 be found to be attached to the 

 potato by a mucous substance 

 which may be drawn out in long 

 threads. According to Hueppe the 

 bacilli cannot form any ropy sub- 

 stances from sugar, but they have 

 an energetic diastatic action. They 

 coagulate the casein in milk in a 

 similar manner to rennet. 



The bacilli are ubiquitous. 



Bacillus lividus (Plagge and 

 Proskauer) . — Rods . 



Colonies blue-black, liquefying. 



In the depth of gelatine they 

 produce a colourless thread in the 

 track of the needle and a violet 

 layer on the surface followed by 

 gradual liquefaction. 



On agar the growth is blue-black, 

 and on potato violet. 



They were isolated from water. 



They are probably identical with 

 Bacillus ianthinus, or merely a 

 variety. 



Bacillus luteus (Flugge). — 

 Short immotile rods. 



Colonies irregular in form, appear 

 brownish under a low power, and 

 yellow to the naked eye. 



In test-tube cultivations they 

 form a yellow growth without 

 liquefying the gelatine. 



They occur contaminating plate- 

 cultivations. 



Bacillus maidis (Cuboni). — 

 Hods 2 to 3 /i in length, singly, 

 in pairs, and in chains ; spore- 

 formation present. 



Colonies granular, with wrinkled 

 periphery ; later, liquefying. 



In the depth of gelatine they 

 produce rapid liquefaction in the 

 track of the needle. 



On agar a dry wrinkled white 

 film spreads over the surface. 



On potato the growth is wrinkled, 

 and later yellowish-brown. They 

 liquefy blood serum. 



They were isolated from human 

 evacuations and infusions of maize. 



Bacillus mallei (p. 452). 



Bacillus megatherium (De 

 Bary). — Rods 2-6 ft wide and four 

 to six times as long, with rounded 

 ends and slightly curved, and in 

 short irregular chains. Transverse 

 division occurs, each segment 

 attaining the length of the original 

 rod. In the fresh state they appear 

 non-articulated, but when treated 



Fig. 205. — Bacillus Megathbrium. 

 {a) A chain of rods x 250, the rest 

 X 600. (6) Two active rods : d and /, 

 succesaive stages of germination; h 

 and I, successive stages of germina- 

 tion. (De Bary. ) 



with a dehydrating agent they are 

 seen to be composed of short seg- 

 ments with granular contents. They 

 are motile. 



Colonies are small and circular, 

 and the gelatine is liquefied. 



In the depth of gelatine the 

 bacilli grow rapidly, forming a 

 funnel-shaped liquefaction in the 

 upper part. 



On agar they form a whitish 

 layer on the surface, and the jelly 

 acquires a dark colour. 



On potato yellowish-white cheesy 

 colonies are formed round the point 

 of inoculation. In cultures there 

 is copious spore-formation. They 

 grow best at 20° C. 



They were isolated originally 

 from boiled cabbage. 



