432 APPENDIX. 



iii. Giving rise to the formation of bubbles of gas. 



iv. Giving rise to a strong putrefactive odour, see p. 433. 



i. Development of Clostridium forms before spore formation. 



(1) Bacillus butyricus) (Hueppe).— One of the forms of bacilli giving rise to 

 butyric fermentation ; found in milk and in fleshy roots, such as turnips, &c., 

 grows on plates in the deeper layers of the gelatine as delicate yellow masses ; 

 which later assume a brown granular appearance ; these rapidly liquefy the 

 gelatine and run together ; on agar-agar they grow as viscid superficial 

 yellow layers ; in gelatine tube puncture cultures rapidly cause liquefaction 

 along the track of the needle, the fluid becoming cloudy ; the superficial 

 layer is greyish-white or yellow, forming a delicate felted mass; grows 

 very rapidly, especially at a temperature of from 35° to 40° C; digests the 

 casein of milk, interferes with the lactic acid fermentation, and gives a 

 bitter taste ; large, thick, very motile rods, with rounded ends of from 3 

 to lo/t in length, and i/x in breadth ; frequently forms chains ; gives rise 

 to well-developed spores. 



(2) The Clostridium butyricutn or Bacillus amylohacter of Prazmowski 

 is morphologically exceedingly like the above organism, but has the charac- 

 teristic of giving off on solid nutrient media a large quantity of gas which 

 has the butyric acid smell ; it is also markedly ana;robic, transforms starch, 

 sugar, dextrine, and lactates into butyric acid, setting free CO2 and 

 hydrogen ; the threads may be unjointed ; gelatine is liquefied, a regular 

 felted scum forming on the surface ; it grows at a temperature of from 

 35° to 40° C. Although one of the organisms first described, this bacillus 

 has not yet been fully investigated. 



ii. No Clostridium forms, 

 (i) Bacillus mesentericus vulgatus. — (Potato bacillus.) Forms rounded 

 or oval colonies, with sharp margins ; on plate cultivations, first some- 

 what transparent, afterwards slightly yellow ; in needle cultures causes 

 liquefaction along the track of the needle from above downwards, this is 

 always more marked near the surface ; a scum forms on the surface, 

 and the growths along the track of the needle sink to the bottom of 

 the funnel ; the fluid is usually turbid ; on potatoes grows extremely rapidly 

 in the form of a wrinkled moist layer ; later becomes somewhat dried, and 

 rather like a crumpled felt; the organism, which is strongly aerobic, is 

 slightly motile, and occurs as small thick rods with rounded ends, arranged 

 in pairs, or sometimes in fours. 



2. Bacillus j^rophilus is very like the above as regards its growth in 

 gelatine, but the colonies are oval and have sharp margins ; on potatoes it 

 grows as a smooth yellow layer, which later becomes crumpled at the 

 margins; slender spore-bearing rods and threads, about 1.4^ in diameter. 



3. Bacillus liodermos (Descrihedhy Fliigge). — Colonies form small irregular 

 heaps in gelatine, and on potatoes a smooth slimy layer ; short bacilli with 

 rounded ends, wliich are actively motile ; in other respects the growth is 

 very like No. I . 



iii. Giving rise to the formation of bubbles of gas. 

 (l) Gasbildender {or gas-forming) bacillus. — An organism found in water. 

 It liquefies gelatine very rapidly, and on plates forms moderately large len- 

 ticulate spaces, in which greyish points may be seen ; these sometimes 

 contain gas ; on the surface the gelatine becomes liquefied, the greyish 

 mass being seen in the centre ; in gelatine tube cultures there is a tube- 



