216 THE MICROSCOPICAL NEWS. 
been used by some of the older workers in microscopy, and was 
not affected by the usual solvents, alcohol, benzole, acetic acid, or 
potash. Can any of your readers inform me of what ingredients it 
was composed ?— Vau. 
MANUAL OF THE INFusoRIA.—The Publishers of Saville Kent’s 
work contemplate issuing an edition with coloured plates if twenty 
subscribers are found. ‘This is an excellent opportunity for Local 
Microscopical Societies, if they have not already purchased the 
work. Orders may be sent to Mr. Thomas Bolton, 57, Newhall 
Street, Birmingham. 
« 
SEPTIC AND PATHOGENIC OrGANISMS.—The Medical Depart- 
ment of the Local "Government Board have just issued an interim 
report by Dr. E. Klein, M.D., F.R.S., “On the relations of Septic 
to Pathogenic Organisms,”—a brochure of 40 pages of exceedingly 
interesting matter. It may be obtained for five stamps from Messrs. 
Knight & Co., 90, Fleet Street, London. 
MounTING FRESH WATER ALG#.—A correspondent well versed 
in the mounting of desmids and other similar vegetable productions 
writes us as follows :—After trying all sorts of media with glycerine, 
carbolic acid, camphor, chloride of calcium, &c., in their com- 
position for mounting fresh water algz, I came to the conclusion 
that none was so good as plain water, with the least addition of 
camphor water to prevent fungoid growths from being afterwards 
developed. 
Most media have a specific gravity greater than that of water, and 
their effect is always to drive the endochrome into the middle of, or at 
any rate away from the walls of the cells, whereas when plain water 
is used its natural disposition remains long unchanged. But I 
am sorry to say that I have never succeeded with azy medium in 
preserving the green colour in any fresh water Algz with any 
degree of certainty. I have some slides of Desmids mounted ten 
years ago, and still as green as grass, and others mounted last year, 
which are already brown, and I cannot tell why this is so. It does 
not seem to depend on the season at which the plants are collected. 
I am not sure whether two precautions might not lead to success 
in this point, and I will make experiments shortly on the matter. 
I would suggest, rst, to use water recently boiled, and then closed 
up in a flask so as to minimise the amount of air dissolved in it; 
and znd, immediately after mounting to put the slide in the dark. 
I have before now had good specimens spoiled by the plants going 
on growing after mounting, and eliminating oxygen from the 
carbolic acid in solution in the water. As I imagine the brown 
colour to be due to oxidation of the endochrome these precautions 
might be of some use. A. W. W. 
