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. 



On potato 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) . Rod s . 



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 (Fliigge). 

 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). - 

 Rods 2 to 3 p. 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 -5 p. 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 MEGATHERIUM. 

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

 x 600. (b) Two active rods : d and /, 

 successive 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 



I of inoculation. In cultures there 



I is copious spore-formation. They 



; grow best at 20 C. 



They were isolated originally 

 from boiled cabbage. 



