182 Influence of Temperature of Liquid Air on Bdcteria, 



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

 cultures, when cooled down in the liquid air for twenty hours, became 

 non-luminous, but on re-thawing the luminosity returned with unim- 

 paired vigour as the cells renewed their activity. Watery emulsions of 

 the photogenic bacteria, on immersion in liquid air for a few minutes, 

 ceased to emit light, but on withdrawal the luminosity reappeared in 

 a very short time. Strips of filter paper soaked in the watery emul- 

 sions and brightly luminous were immersed directly in the liquid air with 

 similar results. The sudden cessation and rapid renewal of the photo- 

 genic properties of the cells, despite the extreme changes of tempera- 

 ture, was remarkable and striking. 



The following experiment was made : — Fifty litres of the laboratory 

 air about six feet from the ground were liquefied at atmospheric pressure 

 in a glass bulb by means of boiling liquid air in vacuo. The tempera- 

 ture reached was about - 210" C. The bulb was then sealed off, the 

 contents being still at a temperature below zero, and was subsequently 

 opened and washed out with sterile broth. A series of plate cultures 

 were made from the broth on nutrient gelatin, agar-agar and sugar agar, 

 and were incubated under aerobic and anaerobic conditions at 22° and 

 37° C. for a period of ten days. The anaerobic plate cultures remained 

 sterile. The aerobic plates yielded forty-four organisms which had 

 survived an exposure to - 210° C. The organisms were representative 

 types of those to be usually met with in the air, viz., moulds, bacilli, 

 cocci, torulse and sarcina3. 



It may also be mentioned that a sample of yeast cell plasma 

 (Buchner's zymase) subjected to - 182° C. to - 190° C. for twenty 

 hours, retained its peculiar properties unchanged, viz., as regards the 

 production of CO2 and alcohol. 



The above experiments show that bacteria may be cooled down 

 to - 190° C. for a period of twenty hours without losing any of their 

 vital properties. 



Further experiments are in progress with the above-mentioned and 

 with other micro-organisms, exposed to the temperature of liquid air 

 for still longer periods of time, as well as to that of liquid hydrogen. 

 These experiments will form the subject of a future communication. 



