Tar cancer in mice. 2, The condition of the skin when modified by external treatment or diet, as a factor in influencing the cancerous reaction / A.F. Watson and E. Mellanby.

  • Watson, A. F.
Date:
[1930]
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Licence: In copyright

Credit: Tar cancer in mice. 2, The condition of the skin when modified by external treatment or diet, as a factor in influencing the cancerous reaction / A.F. Watson and E. Mellanby. Source: Wellcome Collection.

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    TAR CANCER IN MICE. II: THE CONDITION OF THE SKIN WHEN MODIFIED BY EXTERNAL TREATMENT OR DIET, AS A FACTOR IN INFLUENCING THE CANCEROUS REACTION. t A. F. WATSON and E. MELLANBY. From the Pharmacology Department, Sheffield University. Received for publication May 14th, 1930. The present paper is concerned with a consideration of the effect of the local and general condition of the skin of mice, as modified by external treatment or diet, on the carcinogenic activity of tar. METHODS. With few exceptions, the general methods outlined in a previous paper (Watson and Mellanby, 1930) were employed. The technique used for experimentally modifying the local or general condition of the skin is described at the beginning of each section concerned. Unless otherwise stated the animals have been maintained on the control diet, consisting of powdered bread (4 parts), Sussex ground oats (1 part) and minced cabbage (1 part), mixed in an electric mixer and made into a uniformly moist paste with water ; this diet was fed daily and supplemented once per week with cod-liver oil 0'25 c.c. per mouse and mannite 0‘25 gr. per mouse. The standard method of applying the tar to the epilated skin of the animal has been outlined in the previous paper, although in comparative experiments it has been found advisable under certain circumstances to reduce the severity of the tar treatment of both experimental and control animals in order to magnify any differences that may possibly exist in the reaction of the mice to the experimental conditions. Loeb (1924) and Slye (1925) are both of the opinion, for instance, that if an irritant is strong enough it may overwhelm and conceal any inherited resistance to the development of cancer. Similarly, of course, it might be anticipated that any resistance induced by a particular experimental treatment would be masked if the conditions for inducing the tumours were too severe. Accordingly, certain sub-optimum conditions have been used on occasions in the present investigations. Possibly the easiest method of decreasing the severity of the treatment would be to use a diluted tar, although Hieger (1929) has shown that it is necessary to dilute an ether
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