
But in these sodium silicate solutions the supernatant 
fluid invariably remains perfectly clear, month after 
month, though Bacilli, Micrococci, or Torulze may be 
swarming in or upon the flakes at the bottom of the 
tube. 
Another very important difference is this. Inthe 
organic infusions a large proportion of the organisms 
found will exhibit very active movements, but in the 
sodium silicate solutions the organisms are zavart- 
ably motionless, scattered through or upon the flakes, 
and apparently originating where they are found. 
This holds good for Torulze as well as for Micro- 
cocci and Bacilli, and must be regarded as a very 
important point when we see these motionless 
organisms occurring singly, as well as in small 
groups, throughout the flakes. When hundreds and 
often thousands of these motionless organisms are 
thus to be seen; and when it is borne in mind that 
no organisms whatever are to be found within other 
of these tubes (serving as ‘‘control” experiments) if 
their contents are examined within a day or two 
after they have been heated, what conclusions are 
we to draw? If organisms are not there at first, 
after the process of heating, and tf, after an interval, 
they are there in abundance and are invariably 
stationary, clearly they must have developed in the 
sites where they are found. 
Is there any chance of contamination having taken 
place after the heating? None. The procedure has 
been this. The end of the tube has been cut off, 
and if the orifice is narrow some of the deposit is 
shaken out on to a clean microscope slip, which 
