132 Messrs. S. G. Shattock and L. S. Dudgeon. [Feb. 20, 



one. Quot actiones tot protoplasmata. And the same of bacteria, physio- 

 logically considered. How long B. pyocyaneus will live in the dried 

 state in vacuo is an interesting question, and we have a series of vacuum 

 tubes sealed off to keep (excluded from the light) for protracted periods, with 

 a view of testing it. 



In the air-dried state B. pyocyaneus presents no particular longevity. Its 

 death under these circumstances cannot be ascribed simply to its drying. 

 The film may absorb moisture at intervals according to the saturation of the 

 atmosphere, and the bacillus may be killed by a recurrent process of 

 oxidation. Or dissociation may occur in some of the less stable constituents 

 of the protoplasm. In the vacuum tube oxidation would be excluded, but 

 dissociation or autolysis might occur, and eventually prove fatal. 



In the case of Staphylococcus pyogenes aureus, which survives some weeks 

 in vacuo and then dies, something of the latter kind may be assumed, by way 

 of exclusion, to take place. 



It may be pointed out that these differences in resistance to drying 

 in vacuo cannot be ascribed to the chemical differences indicated by Gram's- 

 staining reaction. Staphylococcus pyogenes aureus (Gram positive) is, it is 

 true, more resistent than B. coli or B. typhosus (both Gram negative) but the 

 most resistent of all, B. pyocyaneus, is, like the least, Gram negative. 



The ordinary microscopic examination does not reveal any recognisable 

 change in bacilli which have been long dried. A dried peptone-water film 

 of B. pyocyaneus, made November 26, 1910, and stored in the dark, in 

 a Petri dish, showed, when stained with carbol fuchsin, and examined with 

 1/12 immersion, on June 15, 1911, nothing in which it would differ from 

 a recently made preparation. And the same is true of Staphylococcus pyogenes 

 aureus. 



A similar film of B. pyocyaneus made in July, 1911, was examined in 

 January, 1912, in a hanging drop, which was prepared by" wetting the dry 

 film with germ-free distilled water, and transferring a loop of the suspension 

 to a cover-glass. The bacilli after imbibition of water were of full size, and 

 perfectly normal in form. 



The Persistence of Vitality in Bacteria in the Dried State in vacuo, and the 

 Question of their Resistance in this Condition to Physical Agencies. 



The most fascinating problem in connection with the vitality of bacteria 

 in vacuo is the possibility of their interplanetary life. 



That certain bacteria can survive in a fully dried state in vacuo is as 

 important a fact in this connection as that so many may be frozen at the 

 temperature of liquid air ( — 190° C.) without being killed. 



