368 TUBERCULOSIS AS A TYPE OF BACTERIAL DISEASE 



cultures up to three months old show no acid-fast portions when stained by the Ziehl- 

 Neelsen method. 



Cultural Characteristics. — Grows freely in presence of oxygen, very scanty 

 growth under anaerobic conditions ; on all media, except potato, growth is distinctly 

 more active at 37° C. than at 22° C. ; old cultures, especially those in peptone beef 

 broth, have a faintly feculent odour. On gelatine at 22° C. — Streak culture : obvious 

 growth is seen on third day, at first of an opaque white appearance, later may show 

 a very faint yellowish tinge. Growth sinks slowly into the medium, which gradually 

 liquefies. Stab culture : growth occurs along track of needle in the form of super- 

 imposed colonies, which have a somewhat flocculent appearance. On peptone-maltose 

 agar. — After 24 hours' incubation at 37° C. there is some indication of growth; at 

 22° C. no obvious growth occurs within this period. After 72 hours' incubation at 

 37° C. there is a fair amount of growth, and rather less after incubation at 22° C. 

 The growth, at first of a faint drab or whitish tint, after longer incubation, becomes 

 usually of a faint yellowish colour. Cultures may yield a free formation of aerial 

 hyphse, giving a snowy appearance to the surface of the growth, or the surface may 

 assume a reticulated appearance, without any efflorescence. (For microscopic 

 appearances, see Plate 29.) On inspissated horse-serum.— Growth is comparatively 

 scanty on this medium, appearing after 72 hours' incubation at 37° C. At the end of 

 twenty-eight days' incubation at 87° C. there is a dry, wrinkled, drab-coloured growth, 

 which has sunk slightly into the medium; no liquefaction. On potato. — Growth 

 on this medium is equal at temperature 37° C. and 22° C. ; at the end of 48 hours' 

 growth appears as a brownish or faintly yellowish stain on the medium ; later, 

 growth usually assumes a cafi au lait colour ; there is no pigmentation or 

 erosion of the medium. Surface efflorescence is seen only in cultures incubated at 

 37° C, and not in cultures at 22° C. In peptone beef broth. — After 48 hours' incu- 

 bation at 37° C. the appearance of some filmy growth is seen at the bottom of the 

 tube ; in older cultures growth appears as flocculent, more or less discoid colonies. 

 No pigmentation, (For microscopic appearances, see Plate 29.) In alkaline 

 litmus milk. — Medium at end of 72 hours' incubation at 37° C. is of a faint pink 

 colour ; no coagulation. The pink colour changes to- a dirty white, and the milk 

 clears gradually from the surface downwards, becoming at last of a brown colour. 

 Growth on peptone agar is about equal to that on peptone-maltose agar ; growth on 

 glycerine agar (1 per cent, glycerine) is less free than it is on either of the two pre- 

 ceding media. Diastatic action. — No action of the sort is manifested within fourteen 

 days' incubation at 37° C. Resistance to heat. — Sporulating cultures resist exposure 

 to moist heat at 70° C. for 20 minutes, but are destroyed by an exposure to the same 

 temperature for 30 minutes. Pathogenicity for lower animals.^-Not found patho- 

 genic for rabbits (intra-venous and intra-peritoneal inoculation), for guinea-pigs 

 (intra-peritoneal inoculation), or for tame mice (intra-peritoneal and subcutaneous 

 inoculation), 



2. Streptothrix bominis (Foulerton). 



Isolated from a case of pulmonary infection in a woman (especially from sub- 

 cutaneous abscesses). 



Staining Characteristics. — Takes Gram's stain. A three-months' old culture from 

 glycerine-peptone agar showed no acid-fast portions when stained by the Ziehl- 

 Neelsen metnod. 



Cultural Characteristics. — Growth was obtained in peptone-beef broth and on 

 soUd media under ordinary aerobic conditions ; no growth occurred on tubes of 

 peptone agar and glycerine-peptone agar incubated under anaerobic conditions. 

 Growth is more active at 37° C. than at 22° C. On peptone ayan— Growth very 

 slow and scanty; after several weeks' incubation small whitish, heaped-up, dry- 

 looking colonies, resembling somewhat the growth of B. tuberculosis, are seen. On 

 glycerine agar and maltose-peptone agar. — The amount of growth is very much the 

 same as in the last case, and of much the same appearance. On inspissated horse- 

 serum and inspissated ox-serum. — Growth is very scanty ; the colonies sink slightly 

 into the medium. On potato. — No growth was obtained. In peptone-beef broth, — 

 Small globular colonies appear in the depth of the broth after about six days' incu- 



