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. Gutucosr Bovumion. 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. Guucose AGAR. 1% glucose (c. P.), i a 5 tubes. 
d. Lacrosse AGAR. 1% lactose (c. P.), = i of 2 tubes. 
e. Lirmus SotutTion. 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. (Sutton). Place in flasks or test-tubes and sterilize in steamer three 
times, 1 tube. 
f. DuNHAM’s SOLUTION. 
Sodium chloride 0.5 gm. a until all is dissolved, filter, tube and steril- 
Peptone (Witte) 1. gms. tae; tL tribes, 
Water 100.“ 
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 7 
h. Lirmus Minx. 
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 ¢y>Na0H and rendered slightly alkaline to phenolphtha- 
lein by the addition of {NaOH. eK 
2) Litmus solution is then added until medium is faintly blue. 
3) Tube and sterilize in the steamer for 30-45 minutes on 38 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 any 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 XXXVIN. EFFECT OF REACTION OF MEDIA 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 ce. of a normal solution of hydrochloric acid, and to 
the other three the same arnounts of a normal sodium hydrate. 
