712 



ADDITIONAL SPECIES OF 



forms or degenerative products, are capable of forming spores. In potato 

 cultures these masses are seen to consist of short, plump cells, each one of 

 which contains a highly refractive spore. The segments of a filament divide 

 as in Bacillus megatherium, without any external appearance of division, the 

 new cells growing in breadth rather than in length ; as a result of unequal 

 growth irregular masses are formed, in which later spores are developed. In 

 anaerobic cultures the cells are usually solitary, or, at most, united in pairs. 

 The protoplasm of young cells is fine and granular; in older cells, and espe- 

 cially in unfavorable media, the contents consist of large, shining granules. 



Stains with the usual aniline colors and by Gram's method ; the granules 

 are deeply stained by Kiihne's car bol-methyl- blue solution. 



Biological Characters. An aerobic and facultative anaerobic, lique- 

 fying, usually non-motile bacillus; in bouillon cultures kept at 37 C. a 

 slight to-and-fro movement may be observed. Forms spores. Grows in the 



^ 



FIG. 259. FIG. 260. 



FIG. 25D. Bacillus thalassophilus; culture in nutrient gelatin at end of fourth day; a, drum- 

 rstick forms from gelatin culture; e, bacilli containing spores. (Russell.) 



FIG. 2CO. Bacillus granulosus; young surface colony upon gelatin plate; a, b, c, normal 

 forms from recent gelatin culture; /, /', from an old gelatin culture; g-h, abnormal forms from 

 potato culture at A, spores. (Russell.) 



usual culture media at the room temperature. Upon gelatin plates the col- 

 onies differ considerably in appearance, especially those upon the surface. 

 At first they are usually thin, almost transparent, and leaf -like; under a low 

 power these colonies are seen to be covered with irregular, concentric lines, 

 which are formed by the parallel arrangement of the filaments, and under 

 the microscope resemble the anastomosing "nerves " upon a leaf. Liquefac- 

 tion of the gelatin quickly occurs. The deep colonies are not characteristic, 

 and remain as small, round, shining, opaque masses. The colonies are vis- 

 cid, drawing out into threads, or, when touched with the platinum needle, 

 the entire colony may be picked up. In gelatin stick cultures liquefaction 

 ioccurs near the surface, forming a shallow cavity, at the bottom of which 



