SYMPOSIUM ON RADIO ACTrS'ITY. 77 



changes in the skin. The hairs grow sparsely or not at all; the 

 pores are very fine or absent, from destruction of the glands of 

 the skin; the skin is thinned, with here and there roughened, 

 homy points or patches up to the size of a finger nail, and the 

 surface is reddened from numerous dilated capillaries which 

 show through the thinned horny epidermis. 



We have here as a result of these powerful forms of radiant 

 energy, a picture of extreme interest. The condition is in fact 

 an exact, sometimes an exaggerated picture of the atrophic senile 

 skin, with its dilated blood vessels and senile keratoses. As a 

 matter of fact the picture is so nearly that of senile skin that I 

 was able, in the case of X-ray lesions, to predict that cancers of 

 the skin would be found to develop in them because the keratoses 

 of old age are so frequently the starting point of cancers. It 

 would take us too far from our subject to give all the reasons for 

 the idea, but the identity of chronic radium and X-ray changes 

 in the skin with those of the senile skin, strongly indicate that the 

 senile changes of the skin are in good part the result of the less 

 powerful action over a long period of years of sunlight. Another 

 fact, that is beside our topic, is highly interesting in this connec- 

 tion. Cancers develop in the keratoses of X-ray and radium 

 dermatitis, and in them we have one form of carcinoma which is 

 directly traceable to its exciting cause ; and only by bringing in a 

 deus ex machiua in the form of later infection can one avoid the 

 conclusion that at least in these lesions we have cancer which is 

 not of microbic origin. 



When radium is applied to various pathological lesions in the 

 skin the same phenomena occur that are seen in healthy skin, with 

 the addition that under proper precautions selective destructive 

 effects may be produced upon the diseased tissues. Take for 

 illustration, nodules of tuberculosis or of carcinoma or sarcoma 

 (cancer) in the skin. With proper care in grading the applica- 

 tions a reaction may be produced which will cause these tissues to 

 be entirely destroyed, while this reaction is not sufficient to destroy 

 the normal stroma in which they are situated, or, if it does destroy 

 the normal tissues in the involved area, they will regenerate with 

 the formation of healthy scars. It is also found in itching ano 

 painful conditions of the skin that the applications have a definite 

 anaesthetic effect. 



The microscopic changes in tissues undergoing a radium reaction 

 are even more interesting than the gross changes. In the early 



