The ordinary methods of preserving specimens of eggs and fish, have never proved satis factory. We have obtained the following receipt, and have tested it thoroughly, both for delicate young fry and for fish eggs, and have found it entirely successful, and far superior to the preparations usually employed. It preserves the natural colors in almost their full brilliancy, whereas spirits of any kind destroy them, and both the fish and the eggs are as nearly like what they appear in the water, as it is possible to conceive. For microscopic observations, it is invaluable as it is perfectly transparent and presents the growth of fungus absolutely. Eggs that have been kept in it for weeks, retain every appearance of life, they exhibit the various stages of embryonic development precisely as if they were just taken from the trough, the changed colors of the living or dead eggs are preserved and the outlines of the embryo, its eyes, its membranes and bones are plainly visible. It is said to preserve specimens uninjured for years, but certainly our experience justifies us in strongly recommending it to all who desire to preserve specimens temporarily or for merely microscopic and scientific investi gation, while we have no reason to doubt that it would answer equally well tor a longer time. The objections to any other preparations, are numerous, as every one who has tried them is aware, but this appears to meet every difficulty and can be safely used by any one. In preserving the delicate and evanescent colors of fish, it adds immensely to the value of the specimens, which in the ordinary preserving fluid, were of a dull unattractive and unnatural sameness of hue, that not only destroyed their beauty but rendered them almost undistinguishable. We give the letter as we receive it.

Rochester, N. Y.

The preservative Fluid, which we prepared for you, for the preservation of the ova of fishes, is composed of equal parts of Glycerine and Camphor Water. The Glycerine should be the best quality - (Price's English or Bower's American.) This fluid is very highly recommended by Lionel S. Beale, F. R. S. Mr. Beale has preparations which have been preserved in Glycerine for twenty years. The addition of Camphor Water prevents any tendency to mildew. Another advantage, and one of especial value in the preservation of ova in the Glycerine and Camphor Water fluid, is, that specimens can be prepared and forwarded during cold weather without danger of loss by freezing. Respectfully yours,

C. F. Paine & Co.