vi] PROPERTIES OF THE RADIATIONS W707 
Care has to be taken in handling radium on account of the 
painful inflammation set up by the rays. If a finger is held for 
some minutes at the base of a capsule containing a radium prepara- 
tion, the skin becomes inflamed for about 15 days and then peels 
off. The painful feeling does not disappear for two months. 
Danysz} found that this action is mainly confined to the skin, 
and does not extend to the underlying tissue. Caterpillars sub- 
jected to the action of the rays lost their power of motion in 
several days and finally died. 
Radium rays have been found beneficial in certain cases of 
cancer. The effect is apparently similar to that produced by 
Rontgen rays, but the use of radium possesses the great advantage 
that the radiating source can be enclosed in a fine tube and intro- 
duced at the particular point at which the action of the rays is 
required. The rays have also been found to hinder or stop the 
development of microbes’. 
Another interesting action of the radium rays has been ob- 
served by Giesel. On bringing up a radium preparation to the 
closed eye, in a dark room, a sensation of diffuse light is observed. 
This effect has been examined by Himstedt and Nagel’® who have 
shown that it 1s due to a fluorescence produced by the rays in the 
eye itself’ The blind are able to perceive this luminosity if the 
retina is intact, but do not do so if the retina is diseased. Hardy 
and Anderson‘ have recently examined this effect in some detail. 
The sensation of light is produced both by the 6 and y rays. The 
eyelid practically absorbs all the @ rays, so that the luminosity 
observed with a closed eye is due to the y rays alone. The lens 
and retina of the eye are strongly phosphorescent under the action 
of the 8 and vy rays. Hardy and Anderson consider that the 
luminosity observed in a dark room with the open eye (the phos- 
phorescent light of the radium itself being stopped by black paper) 
is to a large extent due to the phosphorescence set up in the 
eyeball. The y rays, for the most part, produce the sensation of 
hight when they strike the retina. 
1 C. R. 136, p. 461, 1903. 
* Aschkinass and Caspari, Arch. d. Ges. Physiologie, 86, p. 603, 1901. 
° Drude’s Annal. 4, p. 537, 1901. 
4 Proc. Roy. Soc. 72, p. 393, 1903. 
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