210 SPECIAL BACTERIOLOGY 



Bacillus Subtilis (Hay Bacillus). Large motile rods (for Photo- 

 micrograph showing Flagella, see Fig. 81), frequently growing in long 

 straight threads; it is strongly aerobic, and liquefies gelatine media 

 quickly. Optimum temperature, 30; minimum, 10; maximum, 45 C. 



On Plate Cultures, bright greyish-white colonies appear, surrounded by 

 a radiating margin. 



On Agar-Agar, the growth is peculiar, exhibiting a rigid, shrivelled, 

 easily detached coating. Spores form in the middle of the rods, some- 

 what broader but considerably shorter than the mother cell. The hay 

 bacillus is found in the air, water, dust, faeces, hay, etc. To obtain pure 

 cultures proceed as follows : Cut some hay into small pieces, place in an 

 Erlenmeyer flask, cover with water, and cook for fifteen minutes ; by 

 this means all germs are destroyed, except the resistant spores of the hay 

 bacillus. These grow, and a thin membrane of hay bacilli forms in two 

 to three days on the surface of the hay infusion. (See Photomicrograph, 

 Fig. 80.) 



Bacillus Mesentericus (Potato Bacillus). There are three forms 

 of the organism described : 



1. B. mesentericus vulgatus. 



2. B. fuscus. 



3. B. ruber. 



The last form which invests the potato on which it is growing with a 

 rose colour, possesses extremely resistant durable forms, which can 

 endure boiling for five to six hours. The spores are, in comparison with 

 the bacterial cell, very large. The cultural peculiarities resemble those 

 of the hay bacillus. On potatoes the bacillus forms a strong rugged 

 coating. 



Milk is coagulated and peptonised. 



Bacillus Spinosus. Strongly anaerobic motile rods. In gelatine 

 it forms opalescent spherical colonies with bristly outgrowths. The 

 gelatine is liquefied with the formation of gas. The stab culture before 

 liquefaction resembles a hairy caterpillar (Liideritz). The bacillus grows 

 at room as well as at incubator temperature. The spores are formed in 

 the middle of the rods, which become enlarged like a spindle 

 (clostridium). This bacillus is found in garden soil. 



II. MICROCOCCI. 



1. Nutrient Gelatine is not Liquefied. 



(a.) CHROMOGENIC. 



Micrococcus Auranticus. Round to oval cocci, arranged in small 

 clusters. In cultures the colonies are yellow, shiny, club-shaped, and do 

 not extend very far over the media. 



