20 



()i\i;aiiisms wore not killcil. It is imjjorlaiit to remark lliat 

 ill liiose experiments, the emulsion was not frozezn but 

 subcooled. 



Prnc'lia and Brannan (192(1) isolated //. ti/pJiosiis from 

 ice cream kept for 2S months at -20°. 



(Madiii (ISiKS) froze //. prsfis at -20° daily for 40 days. 

 Such repeated freezini;' and thawing did not kill the 

 organisms. 



Kasansky (lcS<)9) found no h)ss of viability in B. pestis 

 after a stay of SVo months at - 31°. 



According to Pictet and Ynng (1884), bacteria, in sealed 

 glass tubes, did not show any impairment of their activity 

 after having been subjected for 108 hours to at least - 70° 

 and for 20 more hours to - 130°. 



In 1893, Pictet reported that he had exposed 30 to 35 

 kinds of bacteria to - 200° and that they had apparently 

 suffered no injurious effects. 



Bouillon suspensions of the vegetative form of B. 

 anthracis and of the bacillus of chicken cholera w^ere im- 

 mersed in liquid air for 15 hours by Belli (1902). No 

 change of the morphological characters nor of the viru- 

 lence of the organisms could be observed. In another 

 experiment the author placed in a sterilized test tube a 

 small piece of spleen from a rabbit wdiich had just died of 

 anthrax, and then immersed the test tube in liquid air for 

 15 hours. The treated s|3ecimen was found to be just as 

 virulent as another untreated specimen from the same 

 spleen. In a last experiment, small strips of filter paper 

 w^ere impregnated with bouillon cultures of B. anthracis 

 and of the bacillus of chicken cholera, and these strips 

 were then suspended in licpiid air for 8 hours. No diminu- 

 tion of virulence could be observed. 



Paul and Prall (1907) found that dried StaphyJococcus 

 pyogenes aureus can remain alive for weeks in a mixture 

 of dry ice and ether, and for 125 days in liquid air. 



Gonococci, held for 10 days at -20° and for 24 hours 

 at -195°, in liquid nitrogen, were found to be viable by 

 Lumiere and Chevrotier (1914). 



