BY R. GREIG SMITH. 615 



siderably, but, generally speaking, those races which produce 

 white growths on nutrient agar (a and j3) consist of cells measuring 

 0-4-0 6 : 2-3 fi. Occasionally a race of this normal type will 

 have broader rods mixed with cells of that breadth. Those races 

 which produce a buff colour on nutrient agar (/^^) consist of a 

 mixture of short, stout and of long rods varying from 1-3 : 2 to 

 10 : 6/x. All cells stain readily, and are not decolorised by the 

 Gram method. The broader cells appear to have a spongy 

 structure, while the narrower cells stain uniformly. The rod 

 forms a small oval and generally central endospore, readily with 

 the white, but slowly with the buff races. Indeed, with the 

 white races, the film on a 24 hours' bouillon culture at 37° consists 

 chiefly of spores. Germination is lateral. The rods are motile, 

 and in bouillon move about with a wriggling motion. In films 

 of fluid saccharose media, the newly germinated rods have an 

 active, darting motion. When films are prepared from a young 

 agar culture, and stained by the night-blue mordant, as advised 

 by Morton (Trans. Jenner Inst, ii.), the majority of the cells are 

 seen to be capsulated, and to have many peritrichous flagella. 

 Sketches of a few typical cells drawn with the camera lucida 

 accompany this paper. The early cultures of the organism in 

 fluid and sometimes in solid media, frequently show coceoid and 

 streptococcoid swollen cells. These, however, have ceased to 

 form in the second, third, or fourth transfer. 



Relation to Oxygen. — There is practically no growth under 

 anaerobic conditions. In Buchner's tubes, the stroke on agar is 

 faint and amceboid, whilst bouillon becomes slightly turbid. Jn 

 the fermentation tube, no growth occurs in the closed limb. 



Agar 2^/a<<5. —Groups a and /3 : The colonies appear white, or 

 grey-white, and are either flat and dry or raised and fatty. In 

 some races the flat, dull colonies become amoeboid and form a 

 raised, moist, glistening margin, and the centre of the colony may 

 become covered with watery globules. In other races the amoeboid 

 colony becomes wrinkled. Microscopically the deep colonies are 

 ragged, woolly, or fibrous, the surface flat colonies are marbled or 

 wrinkled, with a ver}^ irregular filamentous margin. The amoeboid 



