Staining 379 



It usually appears thicker and more variable in length in 

 artificial cultures than in the blood of animals. 



The bacillus is not motile and has no flagella. Hndo- 

 spores are formed upon Loffler's blood-serum. 



It was at first thought that the bacillus produced no spores, 

 but Dunham* found that spores were produced upon blood- 

 serum, and especially upon Loffler's blood-serum bouillon 

 mixture. The spores resist desiccation and exposure to the 

 air for ten months. They stain readily in hot solutions of 

 fuchsin in anilin water, and are not decolorized by a mod- 

 erate exposure to the action of 3 per cent, solution of 

 hydrochloric acid in absolute alcohol. They are oval, and 

 are usually situated near the middle of the bacillus, which 

 is distended because of the large size of the spore and bulges 

 at the sides. 



Staining. The organism stains well with the ordinary 

 stains, and retains the color well in Gram's method. When 

 stained with methylene-blue a granular or vacuolated ap- 

 pearance is sometimes observed, due to the presence of un- 

 stained dots in the cytoplasm. 



Usually in the body-fluids and often in cultures the bacilli 

 are surrounded by distinct capsules clear, unstained zones. 

 To demonstrate this capsule to the best advantage, Welch 

 and Nuttall devised the following special stain: 



A cover is thinly spread with the bacilli, dried, and fixed 

 without overheating. Upon the surface prepared, glacial 

 acetic acid is dropped for a few moments, then allowed to 

 drain off, and at once replaced by a strong aqueous solution 

 of gentian violet, which is poured off and renewed several 

 times until the acid has been replaced by the stain. The 

 specimen is then examined in the coloring solution, after 

 soaking up the excess with filter-paper, the thin layer of 

 coloring fluid not interfering with a clear view of the bac- 

 teria and their capsules. After mounting in Canada balsam 

 the capsules are not nearly so distinct. The width of the 

 capsule varies from one-half to twice the thickness of the 

 bacillus. Its outer margin is stained, leaving a clear zone 

 immediately about the bacillus. 



The bacillus is anaerobic and aerogenic. It grows upon 

 all culture-media at the room temperature, though better 

 at the temperature of incubation. 



* "Bull, of the Johns Hopkins Hospital," April, 1897, p. 68. 



