Liquid Air upon the Bacillus Tuberculosis. 



499 



The experiments, which were carried out in duplicate, lasted over 

 a period of five months, and I am greatly indebted to Dr. Debrand, 

 of the Pasteur Institute, not only for his general supervision of the 

 experimental animals; but also for his kindness in making the 

 autopsy of one complete series as a control. 



A special strain of tubercle, isolated from a human cervical gland, 

 was used for the purpose of inoculations. Sub-cultures of this were 

 made upon potato, and the mclage from these was used throughout 

 the whole series of experiments. This was enclosed in specially 

 made tubes, and submitted to the influence of liquid air as follows* : — ■ 



Tubes A. Six hours continuous exposure to liquid air, without 

 contact. 



Tubes B. Twelve hours' exposure, without contact. 



Tubes C. Twenty-four hours' exposure, without contact. 



Tubes D. Twenty-four hours' exposure with contact, the tubes 

 remaining filled with liquid air during the whole period. 



Tubes E. Forty-eight hours' exposure, without contact. 



Tubes F. One hundred and forty-four hours' exposure, without 

 contact. 



Tubes G. One week's exposure, without contact. 



Tubes H. Six weeks' exposure, without contact. 



Tubes K. Six weeks' exposure with contact, the tubes remaining 

 filled with liquid air duriug the whole period. 



To test the question of successive alternations of temperature : — 



Tubes L. Six alternate exposures of one hour each during twelve 

 hours to the temperature of liquid air and that of 15° C. 



Tubes M. Three alternate exposures as above, followed by six 

 hours continuous exposure to liquid air. 



Tubes 0. Controls. 



The effect of the above treatment, judged by the result of the 

 subcutaneous inoculation of the guinea-pig with an emulsion made 

 from the contents of one of each series of the above tubes, will be 

 shown by the following table. Thirty animals in all were inoculated, 

 and J c.c. of the emulsion was used in each case. 



The question of vitality was tested by making sub-cultures from 

 the tubes after exposure. With the exception of those tubes exposed 

 to alternations of temperature, no difficulty was found in obtaining a 

 luxuriant growth. 



contact is possible. Given that a cell contains a large proportion of water, it is 

 questionable whether the admission of liquid air to the tube containing the 

 organisms would not give rise to the immediate formation around each individual 

 cell of a thin coating of ice which would effectually protect the cell contents from 

 any specific action the liquid air might possibly have upon them. 



* The temperature of liquid air may be taken at — 193° C, the actual tempera- 

 ture to which the organisms were exposed as —186° C. 



