

~ es 
-~ 
_ "'TYNDALL’S EXPERIMENTAL EVIDENCE 223 
large number of test-tubes through the bottom of a 
box with their lower ends protruding, so as to admit 
of the application of heat. The box was closed and 
made air-tight, and a pipette provided for filling the 
tubes with such organic fluids as might be desired. 
_ The air within the box was, as the professor con- 
sidered, absolutely purified from germs by subsidence, 
the interior of the box being coated with glycerine, 
to imprison whatever dust might fall upon it; and 
the completion of this process was determined by 
the use of the electric beam. A connection with 
the outer air was established through bent tubes 
and plugs of cotton wool, which were thought to 
afford adequate protection against the intrusion of 
germinal matter. 
“Why this roundabout and uncertain method of 
procedure was preferred to much simpler well- 
known means it is difficult to say, but in the first 
series of experiments it led to no catastrophe. 
Various infusions were inserted in the test-tubes by 
means of the pipette, which was carefully guarded 
against the passage of air otherwise than through 
wool. The tubes were heated for a few minutes by 
immersion in an oil bath, and left in the laboratory 
to evolve life if they could. The temperature of 
incubation was not taken, but Professor Tyndall 
stated afterwards that a temperature of 90 F. 
was ‘generally attainable’ in the laboratory, and 
that on mild days and in favourable positions 
the temperature to which the infusions were 
subjected reached over 100 F. All of them 
remained barren, including any neutral solutions 
