274 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
microscopic organisms in a bouillon culture, but it is safer 
to exclude a milk from the market when these three tests 
agree: 
“1. Microscopic examination of the sediment shows 
streptococci, diplococci, or cocci. 
“2. The plate from the same sample shows colonies 
resembling streptococci colonies exceeding a count of 
100,000 to a cubic centimetre. 
“3. The bouillon culture from these colonies shows 
long-chain streptococci alone or in great excess compared 
with the other bacteria present. 
“Milk showing in the stained sediment both abund- 
ance of long-chain streptococci and pus should be con- 
demned as unsafe.” 
The bouillon used in this examination may be pre- 
pared as follows: 
“Infuse 500 g. finely chopped lean meat 24 hours 
with 1,000 c.c. distilled water in refrigerator; restore loss 
by evaporation; strain infusion through cotton flannel.” 
(Or, dissolve 5 g. of beef extract, preferably Liebig’s, 
in 1,000 c.c. distilled water.) 
“Add 1 per cent. peptone. Warm on water bath, 
stirring until peptone is dissolved. 
“ Heat over boiling water or steam bath thirty min- 
utes. Restore loss by evaporation. 
“Titrate, adjust reaction to + 1 per cent. by adding 
normal sodium hydrate. 
“Boil two minutes over a free flame, constantly stir- 
ring. Restore loss by evaporation. 
“Filter through absorbent cotton, passing the liquid 
through until clear. Titrate and record final reaction. 
Tube, using 10 c.c. to each tube. Sterilize.” 
