298 BACTERIA AND DISEASE 



certain cows. Morpliology. — A streptococcus; polymorphic; showing tendency to 

 oval and rod-shaped elements, especially in impression preparations. Presence of 

 wedge-shaped, spindle-like, rod-shaped elements in agar and gelatine, and the 

 characteristic of coherent' conglomeration differentiate this streptococcus from others 

 of the same genus. Irregularity in size and shape of elements ; every transition 

 between coccus and bacillus. Coccus shape prevails in bouillon, the bacillary being 

 more common on agar. The streptococcus is stained by simple stains and Gram's 

 method. Cultural characters: Bouillon. — At 37° C. after 24 hours, the medium 

 remaining clear, a single, thick, white-grey mass, or several smaller masses, appear 

 at the foot of the tube ; coherent on shaking the tube, floats through the medium as 

 a flattened bun-like body. Kurth pointed out that when this mass was examined 

 under the microscope, a conglomerate appearance was present. The mass is co- 

 hesive. Gelatine plates and tubes. — Slow growth, forming small grey colonies, 

 circular or oblong, with firm edge, and consisting of closely set coherent mass of 

 cocci. Older colonies become nodular. Non-liquefying. In gelatine at 37° C. the 

 same appearances occur as in bouillon, but often more marked. Chain formation from 

 these cultures is more marked than in ordinary streptococcus. In gelatine at 37° C. this 

 organism grows similar to 8. longus. Agar plates and tubes. — Three types of colonies 

 occur after 24 hours : (a) grey, granular, irregularly-outlined tuherculated colonies ; 

 (6) colonies of similar kind, but having confluent appearance without tubercles ; 

 (c) younger and smaller colonies which have a fine frilling of chains around a more 

 compact coherent centre. The most useful feature for differential purposes is the 

 granular, glossy, coherent centre, combined with tuberculation. Grows more slowly 

 than S. pyogenes, and on the whole its colonies on agar are smaller, more opaque, and 

 more irregular than those of the other streptococci present. Milk. — Rapid coagula- 

 tion ; produces acid. Sometimes fails to clot mUk. A firm, solid clot forms Litmus 

 milk, as a rule, within the first 2 days at 37° C. After 24 hours the acid-production 

 is very strong, and commonly, when there is a clot as well, the lower half of the tube 

 is yellow-white — ^the top layer being pink. This decolorisation of lower half of litmus 

 milk is due to a reducing action of the streptococcus. Chain formation occurs more 

 than in bouillon. The four chief diagnostic features are : (1) the sediment growth in 

 broth cultures ; (2) the rapid coagulation of mUk ; (3) the acid reaction in litmus 

 milk; (4) the character of the agar colonies. Pathogenesis. — Pathogenic for mice 

 and rabbits. After passing through the mouse, the streptococcus takes on a bacillary 

 form (Gordon), and other modifications, including the diminution of conglomeration, 

 occur. Its virulence differentiates this streptococcus from streptococci present iu 

 non-scarlatinal throats, except S. pyogenes, which is more virulent to white mice than 

 S. conglomeratus. Klein holds that this /S. eonglomeratus is causally related to 

 scarlet fever in man, and is wholly distinct from S. pyogenes. Gordon has isolated 

 the latter from the secretion on the surface of the tonsU in a case of chnically mild, 

 uncomplicated scarlatina. It has also been found like the S. conglomeratus in the . 

 nasal and aural discharge of scarlet fever patients. Gordon believes that both strep- 

 tococci may play a part in the causation of scarlet fever, but that & conglomeratus is 

 the more important of the two, and that it occupies a position in the bacteriological 

 kingdom between S. pyogenes and B. diphtheriw. * 



Typhoid Fever 



Typhoid fever is an acute infectious disease characterised clini- 

 cally by continuous fever, with diarrhoea and other symptoms, and 

 anatomically by a more or less extensive ulceration of the Peyer's 

 patches in the intestine (ileum), with swelling of the mesenteric glands 

 and enlargement of the spleen. The lesion of importance is the ulcera- 

 tion of the bowel, partly on account of its origin, partly on account of 



* For full record of Gordon's researches, see Reports of Medical Officer to Loc. 

 Gov. Bd., 1898-99, pp. 480-93 ; 1899-1900, pp. 385-457 ; and 1900-01, pp. 363-404. 



