. Bulletin - United States National Museum. Science. long trial glycerin mounts have proved very unsatisfactory, even when carefully mounted and ringed with a supposedly impervious cement. Diaspine scales.—Diaspine scales are boiled in caustic potash, the method of boiling varying from a few seconds to half a minute1 for the very strongly chitinized species. Specimens thus softened and par- tially cleared are transferred from the tube directly to a microscope slide and care- fully washed with warm water with the aid of a pipette. Washings with 95 per cent alcohol follow, and the scales are the
. Bulletin - United States National Museum. Science. long trial glycerin mounts have proved very unsatisfactory, even when carefully mounted and ringed with a supposedly impervious cement. Diaspine scales.—Diaspine scales are boiled in caustic potash, the method of boiling varying from a few seconds to half a minute1 for the very strongly chitinized species. Specimens thus softened and par- tially cleared are transferred from the tube directly to a microscope slide and care- fully washed with warm water with the aid of a pipette. Washings with 95 per cent alcohol follow, and the scales are then floated to the center of the slide and arranged in a line, with the pygidia pointing in one direction; after which the alcohol IS removed With fig. 147.—One of the , Poiocera fuliginosa. bibulous paper. Before the alcohol is entirely evaporated a small drop of oil of cloves is applied and slightly heated to drive off the bubbles of air and to cause the oil of cloves to penetrate the specimens. The oil of cloves having been removed, a very small drop of balsam is added and a clean cover glass is applied and held in place with a steel clip while the slide is heated for a few seconds over an alcohol lamp to dry the balsam. If care is used, the balsam can be quickly dried, so that upon cooling it is perfectly hard. Fifteen to twenty minutes are ordinarily needed for such preparation. Xondiaspine scales.—In mounting the soft-bodied scales various methods are necessary for clearing the insects on account of the remarkably diverse coverings which the\r produce. With the lac insects and species of the genus Ceroplastes it is often necessary to boil the specimens in chloroform or acetic acid to remove the wax. Mealv-bugs and Lecaniums can be immediately removed to the potassium hydroxide and boiled similarly to the diaspine scales. However, it is frequently neces- sary to boil the specimens for a long period, and also to prick holes through the body wrall to allow the
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