A text-book of bacteriology / by George M. Sternberg.

  • Sternberg, George Miller, 1838-1915.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of bacteriology / by George M. Sternberg. Source: Wellcome Collection.

    177/748 (page 151)
    an air chamber. A little material from a pure culture of the test organ- ism is drawn into each of these capillary tubes by immersing the open extremity in the culture, after having gently heated the expanded end. The end of the tube is then hermetically sealed by heat These tubes are im- mersed in a water bath maintained at the desired temperature for the stan- dard time. The bath is kept at a uniform temperature by personal supervi- sion. At the bottom of the vessel is a thick glass plate which prevents the thermometer bulb and capillary tubes, which rest upon it, from being ex- posed to heat transmitted directly from the bottom of the vessel. To further guard against this 1 am in the habit of applying the flame to the sides of the vessel, and a uniform temperature throughout the bath is maintained by frequent stirring with a glass rod. It is impossible to avoid slight variations, but by keeping my eye upon the thermometer throughout the experiment I have kept these within very narrow limits. . . . No attempt has been made to fix the thermal death-point within narrower limits than 2° C, and in the table the lowest temperature is given which has been found, in the experi- ments made, to destroy all of the microorganisms in the material subjected to the test. No doubt more extended experiments would result, in some in- stances, in a reduction of the temperature given as the thermal death-point for a degree or more. But the results as stated are sufficiently accurate for all practical purposes. 1 The results obtained in these experiments, for non-sporebearing bacteria, are given in the following table. The time of exposure was ten minutes, except for the cholera spirillum and the cheese spi- rillum of Deneke. THERMAL DEATH-POINT OF BACTERIA. Spirillum cholera Asiaticae Spirillum tyrogenum (cheese spirillum).... Spirillum Finkler-Prior Bacillus typhi abdoininalis Bacillus of schweine-rothlauf (rouget)... . Bacillus murisepticus Bacillus Neapolitanus (Emmerich's bacillus) Bacillus cavicida Bacillus pneumoniae (Friedlander's) Bacillus crassus sputigenus Bacillus pyocyanus Bacillus indicus Bacillus prodigiosus Bacillus cyanogenus.... Bacillus fluoresceins Bacillus acfdi lactici Staphylococcus pyogenes aureus Staphylococcus pyogenes citreus Staphylococcus pyogenes albus Streptococcus pyogenes... Micrococcus tetragenus Micrococcus Pasteuri Sarcina lutea Sarcina aurantiaca Centigrade. Fahrenheit. 52° 125.6 53 125.6 50 122. 56 138.8 58 136.4 58 136.4 62 143.6 62 143.6 56 132.8 54 129.2 56 132.8 58 136.4 58 136.4 54 129.2 54 129.2 56 132.8 58 136.4 62 143.6 62 143.6 54 129 2 58 136.4 52 125.6 64 147.2 62 143.6 The following determinations of the thermal death-point of path- 1 Quoted from the Report of the Committee on Disinfectants of the American Pub- lic Health Association, pages 136 and 152.