rUKSIOENT’S ADDIIESS. 
0 
penuanganato of potash, chloroform, and strong alcohol, are speedily 
fatal to the same Uacteria which were ahle to resist the intluence of 
the poisonous gases above mentioned. (Jn the other hand, according 
to the experiments of MM. Gayon and Dupetit, reported to the 
Academy of Sciences in 1881, the microbe which they indentify 
as the one employed in the reduction of nitrates, not only tolerates 
strong solutions of carbolic and .salicylic acids, but ferments them 
w'ith as little concern as yeast ferments sug-ar. This shows that 
what may be food to one microbe is poison to another, and points 
out the idea which is strongly supported by other observation-s, 
that the varieties of organisms in existence are very specific and 
distinctive in their nature, ami hence the study of their life-history 
is no very easy matter. One of their peculiar features is, that 
although it is easy to destroy the life of the actual working 
microbe, it is very difficult to destroy the vitality of the germ or 
spore from wdiich they originate. These latter will resist the 
boiling heat of water for an indefinite time, as also the lowest 
known temperature. (.)no thing certainly will destroy them, and 
that is, actual lire. 
It has long been known that certain low forms of life are 
actively employeil in the production of changes beneficial to 
higher forms of life, notably the part played by Diatomace*, 
Desmidiaceie, etc., in oxidizing and purifying stagnant water ; but 
i\[r. Sorby, a most careful observer, has recently given some 
attention to the work accomplished by minute animals comprised 
under the head of Entomostraca, Ilotifera, and the worm-like larvne 
of insects. Jlr. Sorby found that the number per gallon, and 
percentage relationship of these creatures, mark in a most clear 
manner changed conditions in the water of rivera such as the 
Thames ; the discharge of a certain amount of sew’age being 
indicated by an increase in the total number per gallon, or by an 
alteration in the relative numbers of the difterent kinds, or by 
both. It was proved that these organisms consumed exci’eraen- 
titious matter, and soon died Avithout it. On the other hand, 
when the (piantity of such impurity became excessive, they were 
