408 
Journal of Agricultural Research 
Vol. VTII, No. ii 
cut margin, as do the colonies of R . mesentericus. The appearance is 
characteristic under a power of 90 diameters, a marked folding resem¬ 
bling the convolution of intestinal coils being present. Sometimes this 
folding is less pronounced and the colonies present a peculiar mottled 
appearance, showing distinct denser and lighter areas of growth (PI. 
93 ,B). 
Morphology and micrometry. —In the hanging-drop or hanging agar 
block the organisms are quite distinctly granular, usually large metachro- 
matic granules showing distinctly. The organism occurs singly, in pairs, 
and in long chains. The flagella are distributed over the body. The 
rods are quite variable in size, being 1.3 to 5.0 fx long and from 0.6 to 1.3 ju 
wide. Spores are usually formed in the middle of the rod, although at 
times spores are found nearer one end. They measure from 1.1 to 2.5 
fx in length and from 0.7 to 1.3 ju in width. 
Motility. —The organism is rather actively motile. 
Gram's stain. —The organism is stained by Gram's method. 
Oxygen requirements. —Aerobic and facultatively anaerobic with 
best growth at or near surface of the deep Liborius tube. 
Bouillon. —Growth varies in bouillon. Usually sooner or later a 
luxuriant gray, ground-glasslike, wrinkled membrane forms, extending 
for a considerable distance up the walls of the tube. The medium 
becomes uniformly turbid, increasing in degree for a time and later clear¬ 
ing, usually at the time the membrane forms. Later from the sinking 
of the membrane and clearing of the medium a large amount of viscid 
sediment forms rising from the bottom of the tube as a spiral on agita¬ 
tion. The membrane at the surface may sink and be re-formed many 
times. As the membrane sinks, there is usually left at the surface of the 
tube on the ^alls a ring growth. The membrane is apt to turn yellow 
or brown toward the fifth day and onward. The above characteristics of 
bouillon growth apply also to the various sugar bouillons—namely, glucose, 
lactose, saccharose, levulose, maltose, and the alcohol mannite, not dif¬ 
ferent essentially from B. mesentericus , except that the membrane is 
usually more luxuriant, more wrinkled, and turns brown or yellow 
sooner. The membrane is not, however, so characteristically ground- 
glasslike, and the medium clears sooner. As regards the reaction in 
bouillon and the various sugars and mannite, what was said under 
B. mesentericus applies to this organism. 
Gas production. —-No gas is produced in fermentation tubes of glucose 
or in deep tubes of glucose agar. 
Serum. —Some liquefaction was noted in some of the strains. A 
luxuriant, gray, glistening, raised growth appears over the whole surface 
within 24 hours. Later, the growth turns yellow or brown as liquefac¬ 
tion proceeds and the resulting liquid varies from light to dark amber. 
Potato. —A luxuriant, moist, gray, raised, much-wrinkled growth 
takes place, most pronounced in the butt, especially over the water. 
