446 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



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. Impression 

 preparations are characteristic {see 

 Plate). 



Milk — Rapid coagulation ; pro- 

 duces acid. Sometimes fails to clot 

 milk. 



Litmus milk — A firm, solid clot 

 forms, 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 strepto- 

 coccus. Chain formation occurs 

 more than in bouillon. 



Blood serum — Grows well, pro- 

 ducing colonies. 



Aerobic. 



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 strepto- 

 cocci present in non - scarlatinal 

 throats, except S. pyogenes, which 

 is more virulent to white mice than 

 S. conglofneratus. Klein holds 

 that this S. conglomeratus is 

 causally related to scarlet fever 

 in man, and is wholly distinct 

 from 6". pyogenes. Gordon has 



isolated the latter from the secre- 

 tion on the surface of the tonsil 

 in a case of clinically mild, un- 

 complicated, scarlatina. It has 

 also been found like the 5. con- 

 glomeratus in the nasal and aural 

 discharge of scarlet fever patients. 

 Gordon believes that both strepto- 

 cocci may play a part in the causa- 

 tion of scarlet fever, but that S. 

 conglomeratus is the more impor- 

 tant of the two, and that it occupies 

 a position in the bacteriological 

 kingdom between S. pyogenes and 

 B. diphthericB. The streptococcus 

 of Baginsky and Sommerfeld, and 

 the streptococcus of Class may be 

 different forms of the S. scarlatinoe. 

 Gordon isolated this streptococcus 

 from the throats of scarlet fever 

 patients, and injected it into mice 

 with fatal results, and producing 

 symptoms in accord with those 

 obtained by Klein when experi- 

 menting on mice with the organism 

 obtained from the Hendon cow 

 disease. 



(For full record of Gordon's 

 researches see Reports of Medical 

 Officer to Loc. Gov. Bd., 1898-99, 

 pp. 480-493; 1899-1900, pp. 385- 

 457 ; and 1900-1901, pp. 353-404-) 



TIMOTHY GRASS BACILLUS 

 (Moellei). B. phlei. 



Source and habitat — Isolated from 

 Phleum pratense, Timothy grass ; 

 has also been met with in other 

 plants, in grasses, in dust, etc., 

 and thence into milk. 



Morphology — Rod; 1-4 ix long, 0-2 to] 

 0-5 /i4 broad ; sometimes curved at] 

 angles, in filaments ; club-shaped. 

 Longer in milk culture than on 1 

 blood serum. 



Staining reaction — Acid-fast ; Ziehl- 

 Neelsen method ; takes Gram. 



Motility — Absent. 



