Tar cancer in mice. 1, The technique of the comparative experiment / by A.F. Watson and E. Mellanby.

  • Watson, A. F.
Date:
[1930?]
Catalogue details

Licence: In copyright

Credit: Tar cancer in mice. 1, The technique of the comparative experiment / by A.F. Watson and E. Mellanby. Source: Wellcome Collection.

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    weekly over a period of four months (120 days) and then left for a further period of 360 days, during which time they were kept under careful observation. One group, F, was maintained on the control diet described above. In the other groups, A, B, C and D, the experimental conditions consisted of modifica¬ tions of the diet, in each group, an aliquot part of the basal diet being substituted by a different foodstuff of animal origin. No other factors were varied during the 480 days of the experiment. By referring the dates of the appearance of the tumours and the deaths of the animals to a zero date (day of first tarring) and the simple re-arrangement of the data obtained, the following table can be constructed : Table I.—Data Collected during Course of Experiment lasting 480 Days. Initial number of mice in each group = 95. Column. Period of experi¬ ment (days). i. Number of mice dy tumours mg- without 2. Number of mice dying tumours. with 3. Incidence of tumours. A. B. c. D. F. A. B. c. D. F. A. B c. D. F. 1- 30 12 13 9 13 14 0 0 0 0 0 0 0 0 0 0 31- 60 4 1 10 3 2 0 0 0 0 0 0 0 0 0 0 61- 90 6 3 1 4 1 0 0 0 0 0 0 0 1 2 3 91-120 2 3 1 0 1 0 0 1 0 0 12 5 6 7 6 121-150 1 0 1 0 3 0 1 0 0 1 8 14 5 10 9 151-180 2 4 4 2 1 0 1 0 1 1 16 14 14 19 17 181-210 4 4 5 0 0 4 4 2 3 2 0 5 4 5 10 211-240 2 1 1 1 0 o Ld 5 1 3 1 7 10 5 6 4 241-270 0 2 7 3 5 1*7 7 11 16 6 8 2 1 5 1 3 271-300 1 1 2 1 6 13 r* 4 8 7 13 1 3 0 4 1 301-330 1 5 0 3 0 8 12 b 17 8 1 1 2 1 2 331-360 0 1 5 1 1 / 3 i 6 8 2 0 0 1 2 361-390 1 1 0 2 Li 1 3 1 i 6 8 1 0 1 0 0 391-420 3 0 5 0 1 1 4 i 5 4 0 1 1 0 1 421-450 2 0 0 2 0 2 2 Li 2 1 2 Lj 2 0 0 0 0 451-480 o 1 0 1 0 2 O O 0 1 1 0 0 0 0 0 Totals 43 40 51 36 36 49 54 39 56 57 52 54 44 56 58 A. B. C. D. F. Number of tumour-bearing mice alive after 480 days . .3 0 5 0 1 ,, tumour-free mice alive after 480 days . . .01031 Treatment with tar was discontinued after the 120th day. It will be seen that the greatest incidence of tumours and the greatest number of deaths in the tumour-free and the tumour-bearing mice occur within fairly well-defined zones. The data from such a table can be utilized in various ways, and with other information obtained during the course of the experiment form a useful basis for assessing the influence of the particular experimental condition on the various effects of tar on the animals.