. Laboratory work in bacteriology. Bacteriology. 486 BACTEKIOLOGY. culture over the entire surface. The growth, as a rule, can easily be removed by adding- sterile water, and then gently agitating the liquid. The thick suspension can then be poured out into sterile flasks or drawn up into sterile bulb pipettes (p. 457). To measure out a dose of the growth Pfeiffer employs a small loop (Oese) that will hold about 2 mg. of the material. This would correspond to a loop about I mm. in diameter. A loopful of the growth is stirred up into 1 of bouillon. A fraction of a loop, as }4, is obtained
. Laboratory work in bacteriology. Bacteriology. 486 BACTEKIOLOGY. culture over the entire surface. The growth, as a rule, can easily be removed by adding- sterile water, and then gently agitating the liquid. The thick suspension can then be poured out into sterile flasks or drawn up into sterile bulb pipettes (p. 457). To measure out a dose of the growth Pfeiffer employs a small loop (Oese) that will hold about 2 mg. of the material. This would correspond to a loop about I mm. in diameter. A loopful of the growth is stirred up into 1 of bouillon. A fraction of a loop, as }4, is obtained by transferring 1 loopful to4cc. of bouillon and then taking 1 of the suspension. For the preliminary injections, it is advis- able to employ dead cultures. The suspension can be heated for 1 hour at 58-65°, or it may be shaken up with a few drops of chloroform. If living cultures -are employed, the dose for the first injection must be a very small fraction of the minimum fatal dose. A record must be kept of the temperature and weight of the animal, and, at no time, must an injection be repeated surfMe cultures" before the temperature and weight have returned to the normal. The first effect of an injection is to cause a slight elevation of temperature which is followed by a depression. The temperature may fall to 30° or lower, before death occurs. The animal likewise loses considerably in weight. Cholera.—PfeifEer immunized guinea-pig's by injecting into the peritoneal cavity one-third of an agar culture, sterilized by chlorof orja or by heating at 65° to ten days later, about half a loopful of the living culture is in- jected in the same manner. After a like interval, one loop- ful of the living culture is injected; then, when the animal recovers two loopsful can be given. In this way the dose can be progressively increased till lasting immunity is ob- tained. Guinea-pigs can thus be immunized so as to with- stand 50 or 75 times the fatal dose. When the gu
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