CHAPTER VI. 
PREPARATION OF CULTURE-MEDIA.' 
I. Bouillon. 
Il. Gelatin. 
Il. Agar. 
1. Infuse finely chopped 
lean beef for twenty hours 
with ¢wice its weight of 
distilled water in the re- 
frigerator, say Io0o grams 
of meat, 2000 grams of 
water. 
2. Make up weight of 
meat-infusion (and meat) 
to original weight by add- 
ing water—z.e., to 3000 
grams. 
3. Filterinfusion through 
cloth to remove meat. 
4. Weigh infusion, say 
1800 grams. 
5. Set infusion on water- 
’ bath, keeping temperature 
below 60° C. 
6. Add peptone, 1 per 
cent., 18 grams; salt, 0.5 
per cent., 9 grams. 
7. After ingredients are 
dissolved, titrate ;?_ reac- 
tion probably + 2.3 to 
+ 2.5 per cent. 
8. Neutralize (Fuller's 
method).3 
Ditto. 
Ditto. 
Ditto. 
Ditto. 
Ditto. 
Ditto, and sheet 
gelatin, 10 per 
cent., 180 grams. 
Ditto, probably 
+ 4.0 to + 5.0 per 
cent. 
Ditto. 
Boil 30 grams of thread 
agar in 1 liter of water for 
half an hour. Make up 
loss by evaporation to a 
weight of 1000 grams. 
1. Infuse finely chopped 
lean beef for twenty hours 
with its own weight of 
distilled water in the re- 
frigerator, say Io0o grams 
of meat, 1000 grams of 
water. 
2. Make up weight of 
meat-infusion (and meat) 
to original weight by add- 
ing water—z.e., to 2000 
grams. 
3. Ditto. 
4. Ditto, say 900 grams, 
5. Ditto. 
6. Add peptone, 2 per 
cent., 18 grams; salt, 1 
per cent., 9 grams. 
7. Ditto, probably + 4.5 
to + 4.7 per cent. 
8. Ditto. 
To the 900 grams of 
meat-infusion (containing 
now peptone and salt) 
add goo grams of the 3 
per cent. agar-jelly de- 
scribed at the head of 
this column, 
For notes see page 51. 
50 
