1912] Vilal Kll'erls of Radium atul other Rays. 291 



WEEKLY EVENING MEETING, 



Friday, February 2, li)12. 



Sir James Crichton Browne, M.D. LL.D. D.Sc. F.R.S., 

 Treasurer and Vice-President, in the Chair. 



Sir James Mackenzie Davidson, M.B. CM. M.R.I 



Vital Effects of Radium and other Rays. 



In the year 1902 it was my privilege to deliver a discourse in this 

 place on " A'-rays and the Localisation of Foreign Bodies." On this 

 occasion we shall consider the influence of these rays on living 

 tissues and pass in review, so far as time permits, the effect of various 

 forms of radiation upon living matter generally. 



Heat Rays. — If we are to adopt the chronological order in which 

 these radiations were discovered and applied, we shall have to con- 

 sider in the first place the efPects of light and radiant heat. It is 

 common knowledge that exposure to heat rays will produce changes 

 in living cells, and, if sufficiently intense, will lead to their destruction. 

 In the same manner light also will cause changes in living tissue. In 

 the case of light and heat rays there is no conveyance of material 

 from the source to the object affected. All that occur are wave- 

 motions, set up in the ether of space, or, as it is sometimes called, 

 the " luminiferous ether." One of our greatest statesmen, the late 

 Marquis of Salisbury, who had such a profound knowledge of science, 

 described the ether which fills all space as " the nominative of the 

 verb 'to undulate '." It is the cardinal fact that ether undulates and 

 that waves are produced within it. Isaac Newton thought that light 

 consisted of corpuscles shot out from the sun into space at an enor- 

 mous velocity, but now it is known that light is produced by waves 

 in the ether, although it may be mentioned in this connexion that as 

 we proceed to deal with radium we shall find that corpuscular pro- 

 jections proceeding nearly up to the velocity of hght really do exist. 



Some of the waves which are produced in the ether, impinging 

 upon the Uving tissues, produce effects in a marked degree. Others 

 do not seem to have any effect upon them at all. The rays which 

 affect living tissues include heat waves, some of the light waves, x- 

 rays, and some of the rays of radium. On the other hand, the long 

 waves produced in space-telegraphy — the so-called wireless telegraphy 

 — have no such appreciable effect. A powerful and constant mag- 

 netic field is apparently without influence upon Uving cells, although 

 Professor Silvanus Thompson has shown that if this magnetic field 



Vol. XX. (No. 106) x 



