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 I ) Bacillus butyricus) ( H ueppe) . 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/x in length, and i/t in breadth ; frequently forms chains ; gives rise 

 to well-developed spores. 



(2) The Clostridium biityricum or Bacillus amylobacter 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 anaerobic, transforms starch, 

 sugar, dextrine, and lactates into butyric acid, setting free CO 2 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 vulgatiis. (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 ALrophilus 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 1.4/1 in diameter. 



3. Bacillus liodermos (Described by Fliigge). Colonies form small irregular 

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

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

 very like No. i. 



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



(i) 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- 



