“By the Dimmock process the wings are first acted upon by a saturated solution of the chloride of lime, chlorine being, of course, the bleaching agent. Afterward they are washed in water to which hydrochloric acid has been added, to get rid of the slight deposit of lime. The process is a slow one for thickly scaled, dark-colored insects, and it occurred to me to try a mixture of the chloride and acid, liberating the chlorine gas. The method was absolutely successful, the wings decolorizing immediately and being ready for the slide within two minutes. In fact, very delicate wings can scarcely be taken out quick enough, and need very little acid. The advantage is the rapidity of work and the certainty of retaining the wings entire, the chloride of lime sometimes destroying the membrane in part before the bleaching is complete. The disadvantage is the vile smell of the chlorine gas when liberated by the combination of the two liquids. For quick work this must be endured, and the beauty and completeness of the result are also advantages to counterbalance the discomfort to the senses.”
For further special directions for mounting, for microscopic purposes, different insects and the different parts of insects, representing both the external chitinous covering and the internal anatomy, the student is referred to special works.
Footnotes:
[4] In North America, Kläger pins and Karlsbad pins can be obtained through Mr. John Ackhurst, 78 Ashland Place, Brooklyn, N. Y., and possibly also through Messrs. Blake & Co., 55 North Seventh street, Philadelphia, Pa. The Vienna pins and the Minutien-Nadeln have to be ordered direct through the manufacturer, Mr. Miller.
[5] Montgomery & Co., 105 Fulton street, New York City.
[6]This applies to the use of short pins, which should subsequently be connected through strips of pith with longer pins. For some of the larger micros the long pins may be used directly and a different spreading board employed.
[PRESERVATION OF ALCOHOLIC SPECIMENS.]
[Apparatus and Methods.]—The collections of most value, especially to our various agricultural colleges and experiment stations will be largely of a biologic and economic character, and the interest attaching to a knowledge of the life history of insects will induce many collectors to build up independent biologic collections. Very much of this biological material will be alcoholic, and though many immature states of insects may be preserved by dry processes, still the bulk must needs be kept in liquid. This material may, when not abundant, be kept with the general systematic collection, but experience has shown that it is better to make a separate biological collection, and this is recommended especially for State institutions where the collections may be expected to attain some considerable proportions. In the case of such collections it is very desirable to adopt some method of securing the vials in such a manner that they can easily be transferred from one place to another and fastened in the boxes or drawers employed for pinned insects. For directions in this regard I reproduce from an article on the subject in Insect Life, Vol. ii, pp. 345, 346, which was republished, with slight changes, from my annual report for 1886 as Honorary Curator.[7]
[Vials, Stoppers and Holders.]—The vials in use to preserve such specimens as must be left in alcohol or other liquids are straight glass tubes of varying diameters and lengths, with round bottom and smooth even mouth. The stoppers in use are of rubber, which, when tightly put into the vial, the air being nearly all expelled, keep the contents of the vial intact and safe for years.
Various forms of bottles are used in museums for the preservation of minute alcoholic material. I have tried the flattened and the square and have studied various other forms of these vials; but I am satisfied that those just described, which are in use by Dr. Hagen in the Cambridge Museum, are, all things considered, the most convenient and economical. A more difficult problem to solve was a convenient and satisfactory method of holding these vials and of fastening them into drawers or cases held at all angles, from perpendicular to horizontal. Most alcoholic collections are simply kept standing, either in tubes with broad bases or in tubes held in wooden or other receptacles; but for a biologic collection of insects something that could be used in connection with the pinned specimens and that could be easily removed, as above set forth, was desirable. After trying many different contrivances I finally prepared a block, with Mr. Hawley's assistance, which answers every purpose of simplicity, neatness, security, and convenience. It is, so far as I know, unique, and will be of advantage for the same purpose to other museums. It has been in use now for the past six years, and has been of great help and satisfaction in the arrangement and preservation of the alcoholic specimens, surpassing all other methods for ease of handling and classifying.