REPORT OF THE SCHOOL OF PATHOLOGY 
95 
For a sample of water of unknown purity. 
Make dilutions i in lo and i in lOO before inoculating the gelatine tubes. 
Count the number of colonies after 48 hours' incubation, put the plates back in the incubator, and 
examine again on the following day to make the final estimate of the number of liquefying colonies. 
Carboliz.ed Agar plates to be made in the same way as the gelatine plates. Examine these after 
24.-36 hours' incubation at 42" C. for the Colon bacillus. Look for and count any greyish translucent 
colonies like drops of oil. 
Milk. — Add I c.c. water to a litmus milk tube, heat at jo'' C. to 80° C. for 15 minutes, and 
anaerobically for 18-24 hours. If the culture 'goes' like a culture of Bacillus enteritidis sporogenes 
inoculate a Guinea-pig with 2 c.c. of the whey, (i c.c. of whey for every 200 grs. weight of Guinea-pig)- 
Milk Analysis 
With a sterilized pipette place 10 c.c. of the milk sample in a sterilized test-tube, and proceed 
in the same manner as in testing the water for Bacillus enteritidis sporogenes. 
Carbolized Agar. — Add i c.c. of a 1-1,000 dilution of the milk sample to a carbolized agar tube, 
and proceed in the same manner as in testing the water for Bacillus coli. 
5 c.c. of the milk sample are to be injected into a Guinea-pig subcutaneously. The animal is to be 
examined after 4 weeks for enlarged glands ; if any are found examine the gland juice for the Tubercle 
bacillus. 
The remainder of the milk sample is to be kept in the refrigerator till the test for tubercle has 
been settled. 
Preserved Food Analysis 
Tinned Meats or Fruits or Milk. 
Note whether the top is concave. 
Incubate the tin unopened at 37° C. for 3 days. 
After 3 days' incubation make a small hole and note whether gas escapes, and, if so, the nature of 
the smell. 
Make a larger opening in the lid and note the look of contents. Inoculate a milk tube, carbolized 
agar and ordinary agar tube, and proceed in the same manner as for water analysis. 
Sterilized Milk and Tinned Milk. 
Proceed as for ordinary milk. 
Potted Meats or Foods not hermetically sealed. 
Proceed as for tinned foods, but do not incubate first. 
Shell-Fish 
With sterilized fine-pointed pipette withdraw some of the fluid contents of the shell and inoculate — 
(1) Carbolized agar tube. 
(2) Litmus milk tube, and proceed as for milk and water. 
With a second pipette remove some of the stomach contents, and proceed as above. 
Raw Meats, Cooked Food, &c. 
In all cases examine systematically for B. coli and B. enteritidis sporogenes. 
Special investigations may, however, be necessary under special circumstances. 
The number of samples taken for bacteriological analysis has increased very largely since 
1898. In that year 438 samples were analyzed; in 1899, 664; and in the present year the 
minimum number will be 1,000. These figures do not include the cases of typhoid, diphtheria, 
and tubercle, which are very numerous. Every sample brought to the Laboratory is carefully 
'jntered on a special form, and a report furnished as soon as possible. The following are examples 
of the forms used for food analyses and diagnostic reports. 
