316 IMPORTANT VARIETIES OF FISSION-FUNGI. 



Bacillus mycoides. Fliigge. 

 (Plates 37 and 38, i-iv.) 



Synonym. — Root bacillus. 



Microscopic Appearance. — Rather large rods, scarcely 

 at all rounded at the ends, 1.6-3.6 fi long and 0.8 /u thick. 

 Sometimes arranged in threads (38, m). Forms oval 

 spores. 



Motility. — We have seen no cultures which exhibited 

 active motility. Usually all the individuals are quiet ex- 

 cept a few, which are only detected in motion after more 

 prolonged observation. Also in the stained preparation 

 the impression is given of only a few being provided with 

 flagella. Formerly we believed we had observed entirely 

 non-motile cultures, but can not now demonstrate this. 

 Here belongs the non-motile Bacillus radicosus Zimm. 



Staining Properties. — Stains by Gram's method. 



Requirements as to Nutrient Media. — Slight; also 

 grows without oxygen but scantity. 



Gelatin Plate. — (a) Natural size : In earliest stage the 

 colonies consist of a scarcely perceptible circle of little 

 hairs (37, vi). After one or two days the gelatin is lique- 

 fied a little, while the colonies have become distinctly 

 larger. The hairy circle ramifies more and more, and 

 thicker branches are formed, especially at the center, 

 which, toward the periphery, are replaced by irregular, 

 fine, root-like branches (37, ix). 



(b) Magnified fifty times: Colorless, more or less winding 

 threads, interlacing in a most extraordinary manner. In 

 the center the colony is sometimes felted and opaque. 

 The branchings are only apparent, since always two closely 

 lying threads diverge from each other at the point of 

 apparent branching. 



Gelatin Stab. — It is characterized by delicate little 

 hairs of quite uniform length growing outward, parallel 1 

 to each other, along the stab canal (37, i). The liquefac- 

 tion of the gelatin begins in the form of a saucer and then 



1 In more advanced stages the hairs are often directed upward (37, 

 n). The zone of liquefaction is usually clear or slightly cloudy. 



