EXPERIMENT STATION BULLETINS. 221 



Temperature. — Withstands 80° C. for 20 min., but is killed at 85° C. for 20 min. Its 

 optimum temperature is 28° C.-30 C. Below 16° C. it grows very slowly. 



Colonies. — It forms in a light brown colony in its first stage. Its border is even and 

 the contour circular. Concentric rings soon appear of different shades of density, 

 and from the border radiate fine thread-like processes. Liquefaction sets in and the 

 outline of the liquefied gelatin is irregular and the colony becomes a nucleated mass 

 with long fibers radiating from the nucleus and extending throughout the liquefied 

 portion. The colony in the last stage has few features left of the first stage. In 

 liquefying-, the colony spreads over the surface rather than in a deep cup manner. 



Gelatin tube-cultures. — A very slight growth appears along the line of inoculation. 

 At the top the growth soon spreads out in a wide and shallow funnel and finally 

 liquefies the surface of the tube to the depth of a half inch and then apparently stops 

 or grows so slowly that observation ceases. It is evident that the growth is dependent 

 upon the oxygen supply. 



Agar inclined tube-culture. — A pearly beaded growth occurs along the line of inocu- 

 lation; its color is yellowish white. It finally spreads out in a creamy layer over the 

 surface of the agar. 



Bouillon cultures. — Cloudiness occurs which does not clear up readily. Small 

 crusty patches appear on the surface, and a small amount of sediment rests at the 

 bottom. 



Milk cultures. — Peptonizes milk but slowly. Clears up only after a long time. 



Potato tube-cultures. — A yellowish white growth drying down into a wrinkled scum. 



Blood serum-cultures. — Peptonized completely. 



Growth. — Rapid. 



Pigment. — None. 



Oxygen conditions. — Requires the presence of free oxygen for growth. 



Odor. — Odor of decomposition. 



Acids. — No acids produced in the presence of lactose, glucose or in other media. 



Behavior to gelatin. — Liquefies rapidly. 



No. 32. 



Source. — This micro-organism was found in sample H of Pasteurized milk. 



Form and grouping. — Bacillus. Thickness varies from |m to 1 m, and its length 

 from 2 m to m. It does not form threads or pairs. 



Spores. — Median spores formed and are quickly set free. 



Protoplasm. — The protoplasm is homogeneous, not changing to any great extent at 

 time of sporulation. 



Motion. — It has a tumbling progressive motion. 



Staining reaction. — Stains readily with the ordinary aniline stains. 



Temperature. — Its optimum temperature is 30° C.-32° C. Growth is checked below 

 15° C. It is killed at 90° C. for 20 min., but withstands 85° C. for the same time. 



Coionks. — The colonies are brown and granular at first. The border is regular 

 and well defined. As it grows, there is a thin layer formed over the surface of the 

 gelatin, with an irregular and somewhat indistinct border. At the center is a 

 decided nuclear mass. Developing farther, the gelatin liquefies underneath the 

 colonies, and leaves only the nucleus as a tangible form. 



Gelatin tube-cultures. — The growth starts along the whole line of puncture, a little 

 more rapidly at the surface than at the bottom. Liquefaction then sets in at the 

 surface, forming a broad and shallow funnel: at the same time the growth becomes 

 more pronounced along the lower line of inoculation. The whole surface of the tube 

 is finally liquefied to the depth of a third of the tube, and from this point liquefaction 

 is exceedingly slow. 



Agar inclim d tube-cultures. — It produces a creamy-white and heavy growth along the 

 line of inoculation which spreads out over the surface in scum. As it grows older, 

 wrinkled indentations radiate from the streak. 



Bouillon cultures. — A clouded appearance of permanence. Sediment found at bottom 

 in very minute quantities. A few patches of bacteria are seen floating on the 

 surface. 



Milk cultures. — Peptonization takes place very slowly. 



Potato cultures. — A yellowish white mass appears which dries down into a wrinkled 

 mass. 



Blood Si rum. — Serum is peptonized completely. 



Growth. Rapid. 



Pigmt ni . -None. 



