I 
264 Proceedings of Royal Society of Edinburgh. [sess. 
It appears that certain microbes are able to withstand the severity 
of a low temperature, although their vitalities (proved by a longer 
period of incubation) are impaired. 
being exposed to a temperature of - 110° C. 
Y. Electrical Experiments on Certain Micro-organisms. 
The following results- concerning the action of the electric 
current on the vitality of certain micro-organisms form a 
continuation of those recorded in Part II. of this paper. The 
experiments were performed upon pure cultivations of three micro- 
organisms. 
(1) Bacillus tuberculosis growing in previously sterilised fluid 
blood-serum was killed by an E.M.F. of 2T6 volts. 
(2) Bacterium allii growing in previously sterilised pork-broth 
(neutral) was killed by an E.M.E. of 3*3 volts. 
(3) Bacillus subtilis growing in previously sterilised pork-broth 
(neutral) was killed by an E.M.E. of 2 -72 volts. 
The temperature of the laboratory was 17° C., and the current was 
allowed to pass for ten minutes in each case. 
The “ electrified ” micro-organisms were then “ transplanted ” to 
a certain number of tubes containing the above cultivating media. 
After an incubation, at 35° C., for twenty days, no growths made 
their appearance in any of the tubes. 
The above experiments show that the electric current proves a 
powerful germicide. 
YI. The Micro-organisms of the Atmosphere. 
The method used in these experiments for determining the number 
of “ colonies ” (of micro-organisms) in a known volume of air, was 
that devised by Hesse (Mittheilungen aus dem Kaiserlichen 
Gesundheitsamte , 1883, bd. ii.). 
After August 6, 1888, a similar method to the one described 
by Dr P. F. Frankland in Nature (vol. xxxviii. p, 235), was used 
in the experiments. 
The following three tables speak for themselves : — 
It has been stated that Bacillus anthracis retains its vitality after 
