20 THE BACTERIA OF THE APIAEY. 



bottom, leaving a gray ring of the growtli adhering to the glass. Reaction 

 alkaline. 



Glucose.— The medium in the bulb becomes turbid, while that in the closed 

 arm is uniformly cloudy. A heavy grayish-white sediment is formed. The 

 reaction is at first slightly acid, but in a few days becomes alkaline. Abundant 

 and rapid gas formation takes place, filling usually from one-half to nine-tenths 

 of the closed arm. The ratio of hydrogen to carbon dioxid is approximately 

 1 to 2 ; that is, the ratio of hydrogen to carbon dioxid is less than 1. 



Lactose. — In this medium gas formation takes place more slowly than in 

 glucose. At the end of 8 days one-fourth of the closed arm is filled with gas. 

 The ratio of hydrogen to carbon dioxid is greater than 1. Reaction acid. 



Saccharose. — Gas is formed abundantly and rapidly; more than one-half of 

 the tube is usually filled with gas. The ratio of hydrogen to carbon dioxid is 

 less than 1. Reaction alkaline. 



Levulose. — A rapid fermentation takes place ; more than one-half of the closed 

 arm is filled with gas. The ratio of hydrogen to carbon dioxid is approximately 

 1 to 5 ; that is, less than 1. A slight formation of acid takes place at first, but 

 the reaction rapidly becomes alkaline. 



Maltose. — Formation of gas takes place with the result that at the end of 5 

 days approximately one-half of the tube is filled. The ratio of hydrogen to 

 carbon dioxid will approximate that of 1 to 1. Reaction acid. 



Mamnite. — Gas is formed rapidly and abundantly ; at the end of 5 days the 

 closed arm is usually much more than half filled with the gas. The reaction is 

 at first slightly acid, but soon becomes alkaline. The ratio of hydrogen to car- 

 bon dioxid is approximately 1 to 2 ; that is, less than 1. 



Potato loater. — Gas forms rapidly and fills half the closed arm. The ratio of 

 hydrogen to carbon dioxid is as 1 to 2 ; that is, less than 1. 



Agar slant. — A moderate, grayish-white, glistening, friable growth appears 

 along the line of inoculation, which usually spreads to the sides of the tube. 



Serum. — Moderate gray growth appears, which is confined quite closely to the 

 line of inoculation. Liquefaction takes place slowly after .3 weeks. 



Potato. — A moderate amount of gray fleshy growth covers the slope. The 

 potato is slightly discolored. 



MilJc. — Coagulation takes place after 4 days' growth. Gas is formed. 



Litmus, milk. — A marked production of acid takes place, followed by firm 

 coagulation. 



Gelatin. — A heavy white growth takes place along the line of inoculation ; the 

 surface growth is flat, bluish-white, and spreads with an uneven margin. Slow 

 infundibuliform liquefaction takes place after 2 weeks. 



Acid agar. — A growth takes place. 



Indol. — A trace is sometimes produced. 



Nitrates. — Reduction to nitrites is positive. 



B. coli communis. 



Occurrence. — Pound in the intestine of healthy honey bees. 



Gelatin colonies. — The superficial colonies are blue, lobate-lobulate, and 

 slightly spreading; when magnified they are brownish yellow in the center 

 and more transparent toward the margin; the deep colonies are spherical to 

 lenticular and brownish yellow, with well-defined borders. 



Morphology.— The short rods with rounded ends measure 1.5^ to 2^1 in length 

 and 0.7/t to O.S/j. in thickness. They occur singly or in pairs, stain uniformly, 

 and are motile by means of a few peritriehie flagella. 



