SAPROPHILIC CLASS— Continued. 99 



Bacillus subtilis (Ehrenb.) Cohn. 



Synonyms. Vibrio subtilis Ehrenberg ; Hay bacillus. 



Explanatory. This is a well-known and widely distributed or- 

 ganism. First described by Cohn in 1872. It is almost invariably 

 found on hay, hence the common name. Its spores, like those of the 

 "potato bacillus," are very resistant to heat. A pure culture can 

 usually be obtained by making an infusion of hay or straw and 

 heating it to 80° C. for ten minutes. 



References. F. Cohn, Beitraege Zur Biologic, Bd. I, 1872, 

 Heft 2, p. 175 ; C. 276 ; L. 170 ; L. & N. 317 ; Mig. 2 : 515. 



Morphological characters : 



Sketches. 



1. Form and arkangbment: 

 u. Bouillon 



b. Agar . 



c. Gelatin. 



d. Other media. . 



2. Size: 



3. Staining powers : 



u. Aqueous gentian- violet.. 

 6. Loeffler's methylen-blue. 



c. Gram's stain 



d. Special stains 



i. Motility: 



u. Character of movement. . 

 6. Flagella stain 



5. Spores: 



Special characters: — 



a. Capsules 



b. Involution forms 



c. Deposits or vacuoles.. 



d. Pleomorphism 



