300 J. S. LAWRENCE AND W. W. FORD 



thick moist mass with a silvery sheen which shows black areas 

 at the edges and in old cultures imparts a black tone to the agarr. 

 It liquefies gelatin rapidly, produces a faint acidity in milk 

 which it first coagulates and then slowly digests. On glucose 

 agar it tends to wrinkle sHghtly. It produces a faint acid in 

 glucose, saccharose and lactose fermentation tubes. On potato 

 it grows as a raised brown mass and it also produces a 

 brownish growth on blood serum. 



Thermal death point. The spores withstand boiling one hour 

 in the Arnold sterihzer and a pressure of 20 pounds in the auto- 

 clave. They are destroyed by a pressure of 22 pounds. 



Bacillus pumilus Gottheil 1901 



An organism described by Gottheil (1901) in 1901 as Bacillus 

 pumilus is regarded by Chester as identical with Bacillus mesen- 

 tericus. A culture of Bacillus pumilus received from Krai's 

 collection in Vienna has all the morphological, tinctorial, de- 

 velopmental and cultural reactions of this species. 



Bacillus mycoides Fliigge 1886 



This organism was first described by Fliigge (1886) in 1886 

 and has since then been given other names by various authors. 

 It is not the same as Bacillus ramosus-liquefaciens of Prausnitz 

 which is a distinct species. Bacillus mycoides is quite common 

 in Baltimore and is present in milk, water, soil, and dust. 



Morphology. In young cultures 6 to 8 hours old on plain agar 

 the organisms are homogeneous with square ends and measure 

 usually a little more than 0.5 micron in width by 3 to 6 microns in 

 length. They are distinctly thinner and longer than Bacillus 

 cereus. As the organisms mature the protoplasm appears more 

 granular and a characteristic arrangement in short and long 

 chains is seen. They then resemble the anthrax bacillus. On 

 glucose agar the bacilH are thicker, 0.75 to 1 micron, and usually 

 about the same length. On this medium the protoplasm is 

 converted into globular bodies which do not take the stain and 

 which are similar to those seen in Bacillus cereus. In certain 



