76 ILLINOIS ACADEMY OF SCIENCE. 



once a large number of analagous facts that have been well studied 

 and, because of the more extensive study that has been made of 

 the biological effects of X-rays, enables one to correlate more 

 satisfactorily some of the isolated observations upon the actions 

 of radium. Because the gross effects of radium, which furnish 

 us many valuable facts, can be studied in the skin, and because 

 the effects upon the various tissues of the skin give us the most 

 comprehensive view of the biological effects in general of radium, 

 it is conducive to clearness to consider first the effects of radium 

 upon the skin, meaning by the skin in this connection the human 

 skin or skin of similar structure of other animals. 



When the human skin is exposed for a sufficient length of time 

 to an active radium salt a peculiar and definite reaction is set up, 

 of which the first striking feature is that it does not develop until 

 after a relatively long period of quiescence — as a rule about two 

 weeks. In a skin containing a considerable amount of pigment, 

 there is first an increase of pigment, shown by an ordinary 

 "tanning" of the exposed surfaces. If there are any freckles or 

 pigmented spots in the exposed area, these become darker. Along 

 with this pigment stimulation there occurs a reddening of the 

 skin, with a feeling of irritation and burning such as one has from 

 sunburn. The reaction may stop at this point and after a few 

 days gradually subside ; the redness and irritation diminish, there 

 is some scaling from the surface, and in a few days more no evi- 

 dence of the reaction remains, except the increased pigmentation 

 which, like other pigmentation, is very slow to disappear. 



In this reaction we have had simply the familiar picture of 

 sunburn. But the process, in many cases, goes much farther, and 

 there occurs a reaction which is peculiar to X-rays and radium. 

 After the development of an inflamed, reddened area of skin the 

 surface becomes intensely congested, purplish, and blisters form. 

 At the same time, or before, the hairs loosen and fall out. Next, 

 the blisters rupture and leave a surface covered by a necrotic 

 pellicle, like a diphtheria membrane. And the reaction may go 

 still further, with the formation of an ulcer whose striking char- 

 acteristics are its painfulness and its extreme indolence, showing, 

 it may be for months, no tendency to regeneration. The process 

 may stop at any of the stages described above. If subsidence 

 occurs short of ulceration the skin may again become normal, but 

 after the severe reactions without ulceration, and after ulceration, 

 when healing takes place there may be very distinct permanent 



