The President's Address. 139 



Sir James was desirous of studying the action of intense cold 

 (a few degrees above the absolute zero, which corresponds to 

 — 273° C.) upon the simplest living matter. He found a con- 

 venient corpus vile, or experimental organism, in the bacteria 

 which cause phosphorescence of stale fish, etc. He found that he 

 could freeze cultivations of these bacteria, when their luminosity 

 would cease and all evidence "of " life " disappear, but that on 

 raising the temperature, even after an interval of weeks, the bac- 

 teria immediately became luminous — giving thus a ready test 

 of their return to the active phase of life, and a proof that they 

 had survived the temperature to which they were exposed. He 

 found that phosphorescent bacteria survived an exposure of many 

 weeks to a temperature approaching the absolute zero. In that 

 frozen condition nothing could attack them or injure them ; so 

 long as the low temperature was maintained they were in a state 

 of " arrested movement " — a true suspended animation — like a 

 watch the movement of which is restrained by a needle. When 

 the needle, or the low temperature, is removed, the apparatus 

 works as before. But Sir James Pewar found that there is one 

 agent which can affect the bacteria even when they are frozen hard 

 at the temperature of liquid hydrogen. That is radiant energy of 

 that wave-length which we call violet and ultra-violet. The rays 

 of the blue end of the spectrum destroy the bacteria even when 

 frozen — as he showed by a simple experiment. Kept in the dark or 

 shade, the frozen bacteria survive and become phosphorescent once 

 again on thawing, but if exposed to direct sunlight, or to the blue 

 end of the electric arc, they are killed. 



It seems to me that there is a splendid field here for further 

 work by some of our Fellows. It was long ago shown that direct 

 sunlight inhibits and then kills ordinary putrefactive bacteria. 

 The more precise study of the action of light-rays on protoplasm 

 of various kinds is open to further investigation, as well as the dis- 

 covery of the various means by which the protoplasm of both the 

 lowest and highest animals is protected from the destructive action 

 of light. 



And this brings me to one of the questions of the day, namely, 

 the action of the a, /3, and 7 rays of radium upon protoplasm in its 

 different conditions of nakedness and protection. We shall not get 

 to a real understanding of the possible use of radium-rays as a 

 curative agent until the action of each group, the a, /8, and 7, has 

 been studied experimentally in the most simple cases, so as to de- 

 termine in what way these rays, each apart from the other, affects 

 the elaborate proteid molecules and the ultimate hidden highest 

 combination, concealed in that slimy structure which we call 

 protoplasm. 



I hope that some work on this subject may be undertaken by 

 Fellows of the Societv. It is of no use for the purpose of reallv 



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