BACILLUS MYCOIDES. 317 



becomes cylindric. Upon the surface of the liquefied 

 medium tliere is a thick white film, reminding one of a 

 covering of asbestos. If this falls to the bottom of the 

 liquid, a new one at once forms, so that cultures may be 

 found having many such films. 



Agar Plate. — (a) Natural size: At first the colonies 

 are very like those in the gelatin plate, but more sturdy 

 (37, Vii). The further growth is absolutely irregular, 

 there being found, as well, colonies with a dense center 

 and very distinct main branches, and also those with a 

 delicate central portion, and about this a growth in the 

 form of a circle (37, viii). 



(b) Magnified fifty times : Exactly like the colonies in 

 the gelatin plate. Plate 38, i, represents a colony with an 

 open central part. Plate 38, iv, represents a part of the 

 same magnified 150 times. 



Agar Stab. — Stab: Parallel brush-shaped outgrowths, 

 usually of unequal length, delicate gray, but a little 

 denser than in the gelatin stab (37, iv). Surface growth: 

 Exactly like the colonies on the agar plate; light gray, 

 moist, shining (37, v). 



Agar Streak. — Grayish-white, moist, shining growth, 

 with root-like outgrowths, showing most extraordinary 

 abundant branchings. In a short time it covers the entire 

 surface (37, iii). 



Potato Culture. — Extremely like the potato culture of 

 the Bac. subtilis. It is white, when older yellowish, a 

 little elevated, crummy, dull, provided with a delicate, 

 insignificant fringe at the periphery (38, ii). 



Chemical Activities. — See page 307. There is also no 

 formation of H^S. 



Distribution. — Very common in soil. 



Bacillus subtilis. F. Cohn. (Beitrage, Bd. i, 

 H. ii, 175.) 



(Plates 39 and 40.) 



Common Name. — Hay bacillus. 

 Microscopic Appearance. — Short (1.3-3 /j.), rather 

 thick (0.8-1.2 a), sturdy rods with rounded ends, often 



