. Laboratory work in bacteriology. Bacteriology. BLOOD-SERUM. 467 thermo-regulator is employed to secure a constant temperature. Heat is applied till a temperature of about 75° is reached and this is then maintained for 1 hour. This is repeated on each of three or four successive The time necessary to secure sterilization can be shortened by transferring- the tubes, for a few hours after each heat, to an incubator at 37° as described in connection with the preceding method. Sterilization of serum at 100°.—Serum sterilized at this temperature is opaque white. This, howevei:, does not in-
. Laboratory work in bacteriology. Bacteriology. BLOOD-SERUM. 467 thermo-regulator is employed to secure a constant temperature. Heat is applied till a temperature of about 75° is reached and this is then maintained for 1 hour. This is repeated on each of three or four successive The time necessary to secure sterilization can be shortened by transferring- the tubes, for a few hours after each heat, to an incubator at 37° as described in connection with the preceding method. Sterilization of serum at 100°.—Serum sterilized at this temperature is opaque white. This, howevei:, does not in- terfere with its value as a nutrient medium. The loss of transparency is counterbalanced by the ease with which it can be prepared in larg-e quantities. If inclined blood-serum is heated rapidly to 100° it will solidify, but the mass becomes torn up by gas bubbles due to the expul- sion of carbonic acid. The formation of these bubbles or spaces can be avoided if the serum is first maintained at a temperature of about 80° for some time. For this purpose, they can be inclined in an ordinary air- bath (Fig. 25), or in the apparatus shown in Fig. 65. After keeping the serum at 80° for some time, the temperature should be gradually raised till that of 100' is reached. The tubes are then steamed for 30 minutes on each of 3 suc- cessive Fig. 65. Koch's serum sterilizer. Solidification of serum.—The sterile, fluid serum can be used as such, but more often it is coagulated in an inclined position and employed for streak cultures. The fluid serum should be kept in sealed tubes to prevent evaporation (see. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Novy, Frederick George, 1864- . Ann Arbor [Mich. ] G. Wahr
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