CHAPTER II. 



PHYSIOLOGY OF BACTERIA. 



EXERCISE XXXVII. PREPARATION OF SPECIAL MEDIA. 



The following media will be necessary for the work outlined in this chapter: 



a. GLUCOSE BOUILLON. To ordinary bouillon add 1% glucose (c. P.), tube and 

 sterilize in steamer, not in autoclave, 2 test-tubes and 2 fermentation tubes. 



b. GLUCOSE GELATIN. 1% glucose (c. P.), tube and sterilize in steamer, 6 tubes. 



c. GLUCOSE AGAR. 1% glucose (c. P.), 5 tubes. 



d. LACTOSE AGAR. 1% lactose (c. P.), 2 tubes. 



e. LITMUS SOLUTION. To 10 gms. of the dried material add 500 cc. of distilled water, 

 digest in a warm place, decant clear liquid and add a few drops of nitric acid to produce 

 a violet color. (Button). Place in flasks or test-tubes and sterilize in steamer three 

 times, 1 tube. 



/. DUNHAM'S SOLUTION. 



Sodium chloride 0.5 gm. | fi u u n . dissolved fllt tube and steril . 



Peptone (Witte) 1. gms. \ . . . , 



Water 100. ) ze ' 4 



g. NITRATE 'SOLUTION. 



Sodium chloride 0.5 gm. 



Peptone (Merk) 1 gms. ) 



Potassium nitrate 0.2 [-Filter, tube and sterilize, 3 tubes. 



Water 1,000 j 



k. LITMUS MILK. 



1) Freshly separated milk (or if this is not available, new milk is placed in a sep- 

 aratory funnel in an ice chest over night to allow the separation of the cream and milk 

 then drawn off) is titrated with /jNaOH and rendered slightly alkaline to phenolphtha- 

 lein by the addition of rNaOH. 



2) Litmus solution is then added until medium is faintly blue. 



3) Tube and sterilize in the steamer for 30-45 minutes on 3 or 4 consecutive days. 

 During the summer months particularly very resistant bacterial forms abound in the 

 milk so that it is necessary to increase the number of applications or length of exposure. 

 The efficiency of the sterilizing process should be tested by placing the flasks in the in- 

 cubator for several days to see if anv change occurs, 2 tubes. 



In addition to the above have 15 tubes of bouillon (9 to contain exactly 10 cc. XLI 

 & XLIV), 10 tubes of gelatin, 15 tubes of agar, 6 water-blanks and 5 potato tubes. 



EXERCISE XXXVIII. EFFECT OF REACTION OF HED1A ON GROWTH. 



GENERAL DIRECTIONS. 



a. Melt 6 tubes of gelatin and add, under aseptic precautions, to three of them, re- 

 spectively, 0.1 cc., 0.3 cc., and 0.5 cc. of a normal solution of hydrochloric acid, and to 

 the other three the same amounts of a normal sodium hydrate. 



