76 Influence of Temperature of Liquid Air on Jliero-organisms. 



to be either rendered easier or impeded when the components were 

 applied by alternating right and left stimuli as compared with the 

 method of applying them by coincident right and left stimuli. 



" On the Influence of the Prolonged Action of the Temperature 

 of Liquid Air on Micro-organisms, and on the Effect of 

 . Mechanical Trituration at the Temperature of Liquid Air on 

 Photogenic Bacteria." By Allan Macfadyen, M.D. Com- 

 municated by Professor James Dewae. F.K.S. Eeceived 

 August '2, 1902. 



In previous communications it was shown that an exposure for 

 twenty hours and for a period of seven days to the temperature of 

 liquid air (about - 190" C.) had no effect on the vitality of micro- 

 organisms, whilst an exposure of ten hours to a temperature as low as 

 that of liquid hydrogen (about -252' C.) was likewise without an 

 appreciable effect.* 



Further experiments have since been made in which the influence of 

 the prolonged action of the temperature of liquid air on organisms 

 was tested for a period of six months. 



The bacteria employed were non-sporing forms, viz., B. typhosus^ 

 B. coli communis, and Staphylococcus pyogenes aureus, along with a Sac- 

 charomyces. 



The bacteria were directly immersed in the liquid air, either on 

 cotton-wool swabs enclosed in a perforated metal case, or on small 

 loops of platinum wire. The yeast was washed and pressed, then 

 wrapped up in rice paper, and directly exposed. 



Samples were removed and tested at various intervals up to six 

 months. In no case could any impairment of the vitality of the 

 organisms be detected. The fresh growths obtained were normal in 

 every respect, and the functional activities of the organisms were 

 unaffected. .The typhoid bacillus retained its pathogenic properties, 

 and responded typically to the agglutination test; the colon bacillus 

 exhibited its normal properties • the Staphylococcus aureus produced pig- 

 ment on solid and an active hemolysin in fluid media, whilst the yeast 

 exhibited its fermentative power unimpaired. 



The above experiments show that a prolonged exposure of six 

 months to a temperature of about - 190° C. has no appreciable effect 

 on the vitality of micro-organisms. To judge by the results, there 

 appeared no reason to doubt that the experiment might have been 

 successfully prolonged for a still longer period. 



* ' Roy. Soc. Proc.,' February 1, 1900; ibid., April 5 3 1900 ; ibid., May 31, 1900. 



