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.

    1/16 (page 267)
    TAR CANCER IN MICE: (1) THE TECHNIQUE OF THE COMPARATIVE EXPERIMENT. A. F. WATSON and E. MELLANBY. From the Pharmacology Department, Sheffield University. Received for publication May 14th, 1930. The pioneer work of Yamigawa and Itcliikawa (1915) on the production of the malignant state in the skin'of the rabbit’s ear by means of coal-tar was followed shortly afterwards by that of Tsutsui (1918). who showed that a similar method would produce cancer of the skin in mice. This technique was used in the present investigations, which were undertaken primarily in order to explore the possibility that the initiation and development of cancerous growths might be controlled to some extent by diet. This aspect of the subject has, of course, received much attention, especially in the earlier days of experimental work on cancer, when the method employed consisted of determining the effect of certain dietetic units on the growth of transplanted tumours. More recently, Caspari (1929) and his co-workers have examined some of these effects in detail, and their papers include an extensive survey of the views of other workers in this particular field. It seemed to us, as it has to many others, that the determination of the effects of any experimentally imposed condition was more likely to lead to results when tested on the initia¬ tion and development of what might be regarded as natural neoplasms produced by tar than on the growth of transplanted tumours. It was not anticipated that any large and clear-cut effects would be obtained in the early stages of the work, since these would undoubtedly have been recognized by earlier investigators. It was considered more likely that, working under the conditions chosen, small but unequivocal differences might be observed in the development of the tumours, and it was hoped that, once obtained, it might be possible to simplify the conditions, and thus track down the factor or factors , affecting the cancerous reaction. Now it is well known that the production of tar cancer in mice involves a technique which may be so crude as to conceal small but real differences. Many animals die as the result of a toxaemia set up by the tar, while the very nature of feeding experiments introduces conditions which must of necessity depress on occasions the health i of experimental animals. This latter fact in investigations of this sort is of special importance. Any conditions leading to ill-health and starvation will 11 also tend to depress the growth of cancerous tumours—a fact which most of ;he earlier workers have recognized. In view of these facts it seemed essential that the technique employed should be such that small differences produced by altered conditions could be easily observed, and that as a rule results should not be regarded as satisfactory and specific unless obtained jnder conditions when the general health of the animals in the different