12 THE BACTEKIA OF THE APIAEY. 



(j) Potato water.— To potatoes sliced very thin is added an equal 

 amount of water by weight and the mixture is then boiled. This is 

 btrained and distributed in straight and fermentation tubes. The 

 reaction of the solution was made +1.5 to phenolphthalein. If any 

 of the micro-organisms ferment glucose with the production of gas, 

 fermentation tubes are inoculated to test the fermentation of starch ; 

 if not, straight tubes are inoculated. 



(k) Milk.— If a micro-organism breaks up glucose with the forma- 

 tion of gas, a fermentation tube of milk is inoculated with the 

 culture; if not, straight tubes are used. Separator milk is used. 

 The coagulation of the casein with or without liquefaction is the 

 chief character noted. Very little stress is laid upon the time ele- 

 ment in the coagulation of the casein and the other phenomena 

 which are to be observed in milk. Different samples of milk and 

 the different environmental conditions are factors which vary the 

 length of time at which the different phenomena appear. 



(1) Litmus milk. — The reaction as shown by the litmus and the dis- 

 charging of the color are the chief points observed. 



(m) Gelatin. — The color, degree of growth, the presence or 

 absence of liquefaction, and the form of liquefaction are the chief 

 points observed. The cultures are kept under observation 2 months 

 or longer and, as in serum, the time given at which liquefaction takes 

 place is only approximate. 



(w) Indol. — The cultures are allowed to grow in sugar-free pep- 

 tonized bouillon for 3 to 5 days, and are tested with potassium nitrite 

 (KNOj) and sulfuric acid (H,S04) after the ring method. Too 

 much stress may be placed upon the ability of an organism to form 

 indol. This character has been shown to be a somewhat transient 

 one (3). 



{o) Reduction of nitrates to nitrites. — Cultures are cultivated 7 

 days in a solution of 1 gram of Witte's peptonum siccum and one- 

 fifth gram of sodium nitrate in 1,000 c. c. of tap water. To such a 

 culture and to a control tube are added a mixture of naphthylamine 

 and sulfanilic acid (napthylamine, 1 part; distilled water, 1,000 

 parts: sulfanilic acid, one-half gram, dissolved in dilute acetic acid 

 in the proportion of 1 part of acid to 16 parts of water) . If nitrate 

 is reduced to nitrite, a pink color develops. The control tube should 

 remain clear, or slightly pink — owing to the absorption of a trace of 

 nitrite from the atmosphere. 



PART I. BACTERIA OF THE NORMAL APIARY. 



Before studying the cause of a disease it is necessary that we 

 know what bacteria are normally present, so that later, in studying 

 diseased conditions, a consideration of these nonpathogenic species 

 may be eliminated. In view of this necessity a bacteriological study 



