NOT DESCRIBED IN PREVIOUS SECTIONS. 473 



and opaque, with a whitish, lustre by reflected light. The deep colonies are 

 spherical and opaque and attain a considerable size. In gelatin stick cul- 

 tures the growth resembles that of Friedlander's bacillus i.e., an abundant 

 growth along the line of puncture and a rounded mass upon the surface, 

 forming a " nail-shaped " growth. In old cultures the upper portion of the 

 gelatin is sometimes clouded, and numerous gas bubbles may form in the 

 gelatin. Upon the surface of nutrient agar an abundant, soft, white layer 

 is developed. Upon old potatoes, in the incubating oven, at the end of 

 twenty-four hours a yellowish -white layer, several millimetres thick, is 

 developed, which is of paste-like consistence and contains about the peri- 

 phery a considerable number of small gas bubbles ; this layer increases in 

 dimensions, has an irregular outline, and larger and more numerous gas 

 bubbles are developed about the periphery, some the size of a pea; later the 

 whole surface of the potato is covered with a creamy, semi-fluid mass filled 

 with gas bubbles. On young potatoes the development is different; a rather 

 luxuriant, thick, white or pale yellow layer is formed, which is tolerably 

 dry and has irregular margins ; the surface is smooth and shining, and a 

 few minute gas bubbles only are formed after several days. 



Pathogenesis. Injections of a considerable quantity of a pure culture 

 into the circulation of rabbits and of guinea-pigs give rise to a fatal result 

 within forty-eight hours. 



In his first publication relating to " the bacteria found in the dejecta of 

 infants afflic ted with summer diarrhoea," Booker has described a bacillus 

 which he designates by the letter B, which closely resembles Bacillus lactis 

 aerogenes and is probably identical with it. He says : 



" Summary of Bacillus B. Found nearly constantly in cholera infan- 

 tum and catarrhal enteritis, and generally the predominating form. It 

 appeared in larger quantities in the more serious cases. It was not found 

 in the dysenteric or healthy faeces. It resembles the description of the Ba- 

 cillus lactis aerogenes, but the resemblance does not appear sufficient to con- 

 stitute an identity, and, in the absence of a culture of the latter for com- 

 parison, it is considered a distinct variety for the following reasons : Bacillus 

 B is uniformly larger, its ends are not so sharply rounded, and in all culture 

 media long, thick filaments are seen, and many of the bacilli have the pro- 

 toplasm gathered in the centre, leaving the poles clear. There is some 

 difference in their colony growth on gelatin, and in gelatin stick cultures 

 bacillus B does not show the nail-form growth with marked end swelling in 

 the depth. In potato cultures the Bacillus lactis aerogenes shows a differ- 

 ence between old and new potatoes, while bacillus B does not show any 

 difference. 



"Bacillus B possesses decided pathogenic properties, which was shown 

 both by hypodermic injections and feeding with milk cultures." 



91. BACILLUS C OF BOOKER. 



Found by Booker (1889) in a case of cholera infantum. 



Morphology. Resembles Bacillus lactis aerogenes of Escherich. 



Biological Characters. Resembles Bacillus lactis aerogenes, but differs 

 from it in not coagulating milk; the growth on potato also is more luxuri- 

 ant and the surface is more thickly covered with gas bubbles. 



BACILLI OF JEFFRIES. 



Jeffries, in a study of the alvine discharges of children suffering from 

 summer diarrhoea, isolated a number of bacilli resembling Bacillus coli 

 communis and Bacillus lactis aerogenes of Escherich. He says: 



44 While Brieger's bacillus and the lactic acid bacillus of Escherich were 



not found, a whole group of species in growth, form, and general physiology 



closely resembling them have been isolated. This group is represented by 



bacilli A, G, J, K, P, S, Z ; they seem to form a genus ; the form is very 



33 



