The value of Douglas's medium for the production of diphtheria toxin / by Percival Hartley.

  • Hartley, Percival Horton-Smith, Sir, 1867-
Date:
[1922?]
Catalogue details

Licence: In copyright

Credit: The value of Douglas's medium for the production of diphtheria toxin / by Percival Hartley. Source: Wellcome Collection.

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    In tlie first experiment, 21 litres of broth were distributed into twenty-one double Winchester quart bottles, and all inoculated at the same time. Bottles were withdrawn on the 8th, 10th, 12th, 14th, 16th, and 21st days respectively, and toxicity tests carried out. In the second experiment, 30 litres of broth were dealt with similarly and bottles removed on the 6th, 11th, and 14th days respectively. The strain used was Park Williams No. 8 and the toxicity of the samples was determined by the intracutaneous method (BOmer and Sames (1909 ^o)); (Glenny and Allen (1921 “)). TxVBLE II. Time of Incubation. Toxin Value, LgSOO Dose. Experiment I. Experiment II. c.c. c.c. 6 days .... . . . 0-0003 8 ,, .... 0-0002 . . • 10 ,, .... 0-0002 . • • 11 .. . . < 0-0002 12 ,, ..... 0-0002 . . . 14 ,, .... 0-0003 0-0002 16 .. 0-0002 . . . 21 „ .... 0-0002 At the end of each experiment the whole brew was mixed, filtered, and the minimum lethal dose was determined. In Experiment I. (total volume, 21 litres) the value was O’OOIS c.c.; in Experiment II. (total volume 30 litres) the value was 0'0022 c.c. The earliest date on which maximum toxicity was attained was not accurately determined, but is probably about the end of a week. It was found that no decline in value occurred even after prolonged incubation. This is a point of some practical importance. Bunker working with media containing Witte Peptone showed that there is a point at which toxin development is at a maximum after which potency is lost. P. Hartley and 0. M. Hartley (1922 ^^) found that media containing Parke Davis Bacteriologic Peptone exhibited the same phenomenon, decline in value after the maximum had been reached being very marked in some cases, particularly when small quantities of media were used. The medium described in this paper appears to be free from this defect. Chemical Analyses of Douglas’s Medium. During the course of this work, certain chemical analyses were carried out in order to follow the action of the enzyme on the proteins studied and with the object of comparing the composition of the different preparations of media. A sample of the finished sterilised broth was retained for this purpose. The reaction was ascertained; total nitrogen was determined by Kjeldahl’s method, amino nitrogen by Van Slyke’s method (1913 ^3), also by Sorensen's method (1908 and proteose nitrogen by Hedin's method (1903 ^q. The reaction became a