8 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



description of organisms isolated. 



Micrococcus Orbicularis Flavus. 



Found in virgin soil at the depth of 5 feet. 



diameter. — Shows slight growth in an atmosphere of hydrogen. 

 Morphology. — Large cocci, irregularly grouped. 

 Spore formation not observed. 

 Motility. — Non-motile. 

 Flagella not demonstrated. 



Colonies on gelatin plates. — The colonies first make their appearance about the third day, as 

 minute, pale yellowish dots. x80. No distinction can be made between the deep and surface 

 colonies, except that the latter are larger. They appear as homogeneous, or, sometimes, slightly 

 granular, disks, with even edges and a yellowish hue. The growth is very slow, and at the end of 

 five days the surface colonies are less than 1 mm. in diameter, round, even edged, and only slightly 

 elevated, x SO. They show a homogeneous center, with a finely granular margin. The edges are 

 even and clean-cut. The deep colonies are rather irregular in shape, yellow in color, and finely 

 granular. Here and there they appear to be folded. There is nothing distinctive about either 

 the deep or the surface colonies. The colonies lie in a saucer of liquefied gelatin, which is circular 

 and has smooth margins to the naked eye. 



Agar slant. — A faint yellowish line forms by the second day, which increases rather slowly. 

 At the end of a week a canary-colored layer, some 2 mm. wide, has formed. It has a smooth, 

 glistening surface and rather uneven margins. 



Gelatin stab. — Growth occurs deep down the puncture, and a small yellow button forms on 

 the surface, which is soon floating in a saucer of liquefaction. Liquefaction is 

 rather slow, being complete in four to five weeks. The floor becomes level at the 

 end of a week, and is covered with a yellowish flocculent deposit, while the liquefied 

 ^ gelatin is cloudy. 



5 Potato. — A moist, colorless, very thin layer forms over a large part of the surface 



by the third day. It becomes thicker and turns yellow about the fourth day. It 

 then becomes somewhat granular looking, and is moist and shining, the color being 

 somewhat deeper than on agar. 



Bouillon. — Becomes diffusely cloudy by the second day. A white deposit forms 

 on the bottom, which becomes a faint yellow after some time. 

 Rosolic acid. — Becomes slightly darker after two weeks. 



3 



Gelatin stab. 



Litmus mill;. — No change of any kind can be seen. Reaction amphoteric. 

 Sugar gelatin, deep stab. — Growth quite deep along the puncture. Liquefaction is more rapid 

 than in plain. No gas formed. 



Tndol. — Faint reaction with both sulphuric acid and sodium nitrite. 



Relation to temperature. — Grows more rapidly at room temperature than in the incubator. 



Bacillus Aurescen;: - . 



Found in virgin soil at the depth of 30 inches. 



Character. — Strict aerobe. No growth in an atmosphere of hydrogen. 



Morphology. — Short, straight rods with oval ends, making the cells spindle shaped. Length 

 from two to three times as great as breadth. Found singly. 



Spore formation not positively demonstrated. In some of the rods are seen oval, bright spots 

 which resemble spores somewhat. 



Motility very slight. 



Flagella not demonstrated. 



Colonies mi grin I in jilntis.— Colonies seen at the end of thirty-six to forty hours as minute 

 whitish points, which may easily escape observation. x80. No distinction can be made out 

 between the deep and surface colonies at this stage. They appear as coarsely granular disks of 



