27 
activity of the living organisms. How far this may go it 
would he absurd to attempt to say, and I never have 
much hope of a man who writes about the future of 
truth ; he evidently attempts too much. I am satisfied to 
bring forward such facts as I know in the present, so 
that chemists may not be too late in attending to the new 
ideas. 
The water must not have too much gelatine in it, if so 
the action is stopped. It must not have too little, if so the 
gelatine becomes liquid too soon and the action of the in- 
dividual centres is not observed. When a centre acts it 
makes around it a sphere in some waters, and the sphere 
which has the appearance of a thin vesicle is filled with 
liquid. These spheres form in a day or two according to 
the water, and at the bottom is a white mass containing 
active bacteria chiefly. The liquid filling the spheres may 
be taken out by a pipette and examined, as also the bac~ 
teria which lie at the bottom. 
I have not examined a sufficient number of waters to 
give general rules, but I hope to do so. It is an investiga- 
tion which would properly belong to Professor Koch, and I 
should not have touched it had I not found that it brought 
into use my own enquiries as to fermentation, which were 
earlier, but may now be considered only a supplement to 
Dr. Koch’s. This is by the use of sugar in addition to the 
gelatine. By this means a very great amount of gas is 
developed and retained in the gelatine. The striking 
amount of spheres and gas bubbles render the examination 
of water by this method less dependent on the opinion 
of the operator, and a photograph may be taken of each 
specimen and the result preserved as evidence. 
At the same time I know that it is necessary to examine 
waters of various kinds before we make or find rules, and 
this slight account is a mere beginning. I have as yet 
examined no chalk water for example, but have been 
