recognized tendency of carcinoma to develop as a result of long continued irritation of any sort. It is probably true, however, that in the effects of actinic energy (in¬ cluding, as it does, light) we have the most important cause of epidermal cancer. The prophylaxis of a;-ray carcinoma consists, of course, in avoidance of undue exposure to the rays. The person who is nearest to the danger is the radiographer, who uses enormous quantities of this form of radiant energy in making skiagraphs.

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... in particular, should avoid exposures, and should by the use of shields con¬ fine the rays closely. Fortunately, as the Eoentgen