NON-PATHOGENIC BACILLI. 



GUI 



Morphology. Bacilli from 2 to 5 jn long and 0.5 to 0.7 /* thick; often 

 grow out into long, flexible filaments. 



Biological Characters. An anaerobic, liquefying, non-motile bacilhis. 

 Grows rapidly at the room temperature, in the absence of oxygen, in the 

 usual culture media. In bouillon cultures the thickness of many of the 

 rods is increased to 1 or 1.2 /*, and in these small, round, refractive bodies 

 are seen at the ends, or in a linear series, which are probably spores. The 

 addition of two per cent of grape sugar to culture media 

 is favorable to the growth of this bacillus. In gelatin 

 cultures development occurs at a distance of one to 

 two centimetres below the surface ; at the end of two 

 days, at 20 C., punctiform colonies are developed; 

 these, when not too close together, attain a diameter of 

 2 to 2.5 millimetres; they are filled above with trans- 

 parent liquid gelatin and below with a whitish mass of 

 bacteria. In gelatin stick cultures a row of spherical 

 colonies is developed along the line of puncture ; these 

 increase in diameter from above downward. In nu- 

 trient agar opaque colonies are developed within 0.5 to 

 1 millimetre of the surface ; these are tabular, almond- 

 shaped, or whetstone-shaped, and have a tolerably 

 smooth contour at first ; later they are irregular in out- 

 line. Blood serum is slowly liquefied by this bacillus. 

 In agar cultures a few gas bubbles are developed, and 

 also in blood serum. In bouillon a decided putrefac- 

 tive odor is developed.. Not pathogenic for mice. 



FIG. 233. Bacillus li- 

 quefaciens parvus; col- 

 ony in nutrient agar. 

 X 60. (Luderitz.) 



408. BACILLUS RADIATUS (Liideritz). 



Obtained from garden earth by inoculations in mice and guinea-pigs. 

 Morphology. Bacilli with round ends, from 4 to 7 /* long and about 0.8 

 H thick ; often grow out into long filaments, which are seen to be composed 

 of separate segments. 



Biological Characters. An anaerobic, liquefying, motile bacillus. Move- 

 ments are less active than in Bacillus liquefaciens magnus, and only ob- 

 served in specimens from a recent culture. Spores are developed in the sin- 

 gle rods only not in the filaments; they are from 1.2 to 2 n long and 0.8 to 



0.9 n thick, and are centrally located in the 

 rods; the spore-bearing bacilli are somewhat 

 thicker than others, but do not acquire a spin- 

 dle shape. Grows in the usual culture media 

 at the room temperature when oxygen is ex- 

 cluded. The addition of two per cent of 

 grape sugar is favorable to the development 

 of this bacillus. In test-tube cultures in nu- 

 trient gelatin, at 22 C., colonies are developed 

 to within one or two centimetres of the sur- 

 face ; when these are numerous the gelatin is 

 penetrated throughout, below the limit men- 

 tioned, with numerous glistening threads, and 

 within two or three days is liquefied; some 

 gas accumulates beneath the layer of solid 

 gelatin above ; later liquefaction extends to the 

 surface, and the liquefied gelatin, which at first 

 is clouded, gradually becomes transparent from 

 a deposition of the suspended bacilli. When only a few colonies are developed 

 the growth resembles that of the mycelium of a fungus, the margin consist- 

 ing of interlaced filaments, while the centre shows commencing liquefac- 

 tion; new centres of development are formed by the filaments wnich pene- 

 trate the gelatin, and this is soon completely permeated and at the same 



FIG. 234. Bacillus radiatius; 

 young colony in nutrient gelatin. 

 X 60. (Luderitz.) 



