KINDS OF BACTERIA IN THE SOIL 127 



frequently united into short threads. It is aerobic, motile, stains 

 by Gram's method, and forms small spores i to i . 2 /A long and 

 .6 broad. 



Gelatine. Surface colonies round, with greyish-white crumpled 

 skin, which soon sinks in the liquefied medium. The edges of 

 the colonies are not finely radiated as in Bs. subtilis, but are 

 seen to be irregularly lobed when magnified ( x 50). 



The stab liquefies in the form of a narrow tube, the surface 

 being covered with a greyish membrane. 



Agar. Surface colonies greyish, round, moist, and slightly 

 elevated, becoming drier and wrinkled ; deep colonies, round or 

 spindle-shaped. 



Potato. The growth is abundant, usually greyish or yellowish, 

 glistening, and very much crumpled and twisted. Some varieties 

 produce a pink, brown or blackish colour. 



Bouillon. Slightly turbid, with a strong whitish film on the 

 surface. 



Milk is generally coagulated slowly, and rendered alkaline and 

 slimy ; the curd is peptonized after a time. 



Micrococcus candicans, Fliigge, is a coccus very widely dis- 

 tributed in the air, water, and soil. The cocci are i to 1.2 ft in 

 diameter, usually single or collected in small irregular clumps. 

 It is an aerobic organism, grows well at room temperature, and 

 is stained by Gram's method. 



Gelatine. The surface colonies are non-liquefying, round, in 

 about a week 2 to 3mm. in diameter, raised, moist, and milk-white. 



The deep colonies are small, .3 to .5 mm. in diameter, round 

 or lens-shaped, and opaque. 



The stab is thread-like and beaded. 



Agar. The colonies are similar to those in gelatine, but whiter 

 and more raised. 



Potato. A dense white, oily growth with wavy margin, extending 

 little. 



Bouillon. Generally very turbid at first, ultimately becoming 

 clear with sediment and a surface pellicle. 



