184 THE EVOLUTION OF LIFE 
periments destined to test the contaminating effect 
of boiled tap-water may be gathered from the 
following observations :— 
In 1883, when making other experiments of an 
allied nature, I was anxious to ascertain what would 
be the result of simply boiling tap water in ordinary 
flasks previously cleaned therewith, before adding 
pure urine and then exposing the vessels to a rather 
high incubating temperature. 
Urine of medium acidity was passed with all 
proper precautions (as dictated by Pasteur) into one 
of the flambé receivers used by Lister, and im- 
mediately replugged. 
Three flasks were two-thirds filled with tap water, 
and the fluid in A was boiled for 5’, in B for 10%, 
and in C for 15’, so as to imitate the ordinary 
conditions to which the walls of experimental vessels 
had previously been subjected. When the contents 
of each flask had been boiled for the time indicated 
the boiling water was poured out, some pure urine 
from the receiver was quickly introduced, and each 
flask (having been plugged with carbolised cotton 
wool) was put into an incubator at a temperature of 
about 113° F. 
The results were as follows: A in 3? days 
became turbid, and was found to contain Micrococci 
only ; B became turbid in 34 days, and contained 
Micrococei only ; while C became turbid in 2} days 
and also contained Micrococci only. 
These results surprised me much, first at finding 
Micrococci only, instead of Bacilli, and secondly, at 
finding that the fluid in the flask in which water 

