Diagnostic methods, chemical, bacteriological and microscopical, a text-book for students and practitioners . , it must be rememberedthat many epidemics of milk-borne disease, such as typhoid fever and strepto-coccic sore-throat, may arise owing to improper handling of the milk or toinefficient pasteurization.^ The methods of examining milk for bacteriologic differentiation are thesame as for any other fluid and will be discussed in the next chapter. It is,not infrequently, a matter of importance to the general practitioner and ofuntold value to health officers to determine the number of bacte
Diagnostic methods, chemical, bacteriological and microscopical, a text-book for students and practitioners . , it must be rememberedthat many epidemics of milk-borne disease, such as typhoid fever and strepto-coccic sore-throat, may arise owing to improper handling of the milk or toinefficient pasteurization.^ The methods of examining milk for bacteriologic differentiation are thesame as for any other fluid and will be discussed in the next chapter. It is,not infrequently, a matter of importance to the general practitioner and ofuntold value to health officers to determine the number of bacteria in the milksupplied to the community. The outline of the method to be followed in thiswork is as follows: Collect the specimen as freshly as possible. Keep it on ice from the timeof collection until you are ready for the examination. Sterilize a quantity ofdistilled water in the autoclave. Plug a number of pipets (i and 10 ) withcotton and sterilize in the hot oven. A number of Erlenmeyer flasks, pluggedwith cotton, a 100 graduate, and a number of Petri dishes are sterilized atthe same Fig. 165.—Wolfhiigels colony counter. By means of the graduate place 99 of sterile distilled water in an Erlen-meyer flask, 90 in a second and 99 in a third and replace the means of a sterile i pipet transfer i of the well-shaken specimento flask number i. The dilution of the milk in this first flask is, therefore, ito 100. Shake this dilution thoroughly and transfer 10 of this dilution, bymeans of a pipet, to the second flask containing 90 of water. The seconddilution is i to 1000. By means of a second i pipet transfer i of the i to100 dilution to the last flask, containing 99 of water, thus obtaining a dilu-tion of I to 10,000. These dilutions are usually all that are necessary. Othersmay be made as desired. In the examination of the best market milks, theI to 100 dilution is sufficient. Liquefy a number of tubes
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