1912.] Certain Results of Drying Non-sporing Bacteria. 133 



Particulate life, whether microscopic or •ultra-microscopic, if free under 

 interstellar conditions, would exist in vacuo, and, either in a dried state, or 

 impregnated with water, it would be cooled at a temperature certainly as 

 low as that of liquid air. 



The external agencies adverse to life in such circumstances resolve 

 themselves into the action of the solar rays : heat, light, ultra-violet, and the 

 corpuscular radiations. 



Heat. 



If the inoculated slips of B. pyocyaneus in sealed vacuum tubes be 

 submitted to the action of heat, the vulnerability of the bacillus to this 

 agency is not found to be lessened. It has long since been established that 

 many bacteria, even of the non-sporing kinds, withstand a higher tem- 

 perature in the dry state than in the wet. Suspended in a fluid medium, 

 B. pyocyaneus is killed by a temperature of 60° C. after an hour's exposure. 



In testing the effect of heat upon this bacillus in the dried state, we 

 commenced with a temperature which is lethal to all non-sporing pathogenic 

 bacteria, in order to ascertain whether its resistance in vacuo, if exalted, was 

 exalted in a pronounced degree. 



July 20, 1911. — A vacuum tube containing an inoculated slip of 

 B. pyocyaneus which had been sealed off on July 17 and kept in the dark 

 was baked in the hot-air oven for three hours, between 102° and 104° C. 



No growth occurred from the slip when transferred to litmus glucose 

 broth and incubated at 37° C. 



A control slip, prepared on July 20, and baked simultaneously for the 

 same time in a test-tube, over which a second larger tube was inverted, for 

 protection, likewise proved to be sterile. 



. In the following experiment, the air-dried films of B. yyyocyanms were 

 subjected to a temperature of 100° C. in a water bath, for considerably 

 shorter periods. 



January 6, 1912. — A series of slips were prepared from a 24 hours old 

 peptone water culture of B. pyocyaneus in the usual manner. Three were 

 then transferred, each to a long sterilised test-tube of thick glass ; the tubes 

 were thereupon sealed in the blowpipe flame by heating each at a con- 

 siderable distance below the open end. The three tubes were, in the next 

 place, submerged by means of strips of lead in a vessel of warm water and 

 boiled for 15, 30, and 60 minutes. One end of the tube was cut off with 

 a file, and the slip transferred to a tube of litmus glucose broth, and 

 incubated at 37° C. 



After this, a control slip from the Petri dish was placed into another tube 



