Juno 8, 1900.] Dr. Allan Nacfadycn on Bacterial Life. 457 



in the caso of tho phosphorescent organisms tested. The cells emit 

 light which is apparently produced by a chemical process of intra- 

 cellular oxidation, aud the phenomenon ceases with the cessation of 

 their activity. These organisms therefore furnished a very happy 

 test of the influence of low temperatures on vital phenomena. These 

 organisms when cooled down in liquid air became non-luminous, but 

 on re-thawing the luminosity returned with unimpaired vigour as the 

 cells renewed their activity. The sudden cessation and rapid re- 

 newal of the luminous properties of the cells despite the extreme 

 changes of temperature was remarkable and striking. In further 

 experiments the organisms were subjected to the temperature of 

 liquid air for seven days. The results were again nil. On re-thawing 

 the organisms renewod their life processes with unimpaired vigour. 

 We had not yet succeeded in reaching the limits of vitality. Prof. 

 Dewar kindly afforded the opportunity of submitting the orgauisms 

 to the temperature of liquid hydrogen — about — 2."»0° U. The same 

 series of organisms was employed, and again the result was nil. This 

 temperature is only 21° above that of the absolute zero, a temperature 

 at which, on our present theoretical conceptions, molecular movement 

 ceases and the entire range of chemical and physical activities with 

 which we are acquainted either cease, or it may be, assume an entirely 

 new role. This temperature again is far below that at which any 

 chemical reaction is known to take place. The fact then that life 

 can continue to exist under such conditions affords new ground for 

 reflection as to whether after all life is dependent for its continuance 

 on chemical reactions. We, as biologists, therefoie follow with the 

 keenest interest Prof. Dewar's heroic attempts to reach the absolute 

 zero of temperature ; meanwhile his success has already led us to re- 

 consider many of the main issues of the problem. And by having 

 afforded us a new realm in which to experiment, Prof. Dewar has 

 placed in our hands an agent of investigation from the effective use of 

 which, we who are working at the subject at least hope to gain a little 

 further insight into the great mystery of life itself. 



[A. M.] 



Vol. XVI. (No. 91.) 2 h 



