28 
confined chiefly to the Manchester district, hill water, 
impure brook and pond water, Mersey, Irwell, and Medlock 
water, and canal water. In certain specimens of Manchester 
supply the spheres appear on some days very few, on other 
days the amount is enormous and heavy, the whole of the 
tube in which the experiment is made is filled with spheres. 
At such times the water is highly impure and complained 
of by the public. We have a very easy proof therefore of 
the value of this test. 
The photograph would be a visible report made by nature 
when the water has active organisms in it. The globules do 
not show themselves in strong sewer water, but the whole 
mass becomes turbid and the surface of the gelatine becomes 
liquid and full of life. This liquid condition gradually 
increases until the whole is reached. We have therefore 
two striking conditions well marked out. 
A third may be said to exist, but it is often a mere 
beginning of the globules. This is shown by the formation 
of a small white opaque point. If this point is examined it is 
seen to be full of life like the lower part of the spheres and 
the fluid portion of the gelatine when this fluidity begins 
on the surface. 
I find, also, that the solidity or fluidity of the gelatine is 
an important indication. This is known by the depth to 
which a certain weight will sink in it. 
I use the word bacteria at present because, although I 
have observed various forms, I do not intend to investigate 
the separate functions of each. 
At present this mode of examining water seems to me to 
be far more important than the chemical, more decided and 
telling, but we cannot neglect the chemical. 
An account of a few specimens is given here. 
Specimen 1. — 25 cc. gelatine solution = 2 1 p.c. solid + 25 
cc. distilled water 4* 5 mgms. sodium phosphate. 
After 2 days a few white spots appeared. 
