_Mounting Specimens for the Microscope._--The study of the minuter forms of insect life, including Parasites, Thysanura, Mallophaga, the newly hatched of most insects, etc., requires the use of the microscope, and some little knowledge of the essentials of preparing and mounting specimens is needed. The subject of mounting the different organs of insects and the preparation for histological study of the soft parts of insects opens up the immense field of microscopy, the use of the innumerable mounting media, the special treatment of the objects to be mounted, staining, section-cutting, and many other like topics, a full description of which is altogether out of place in the present work. Anyone desiring to become thoroughly versed in the subject should consult some of the larger manuals for the microscopist, of which there are many. For the practical working entomologist, however, a knowledge of all these methods and processes is not essential, and in my long experience I have found that mounting in Canada balsam will answer for almost every purpose. The softer-bodied forms will shrink more or less in this substance, and it is frequently necessary to make studies or drawings of them when freshly mounted; or, if additional specimens are preserved in alcohol, they will supplement the mounted specimens and the material may be worked up at the convenience of the student. The materials for the balsam mounts may be obtained of any dealer in microscopical supplies. They consist of glass slides, 3 inches by 1 inch, thin cover-glasses of different dimensions, and the prepared balsam. The balsam is put up very conveniently for use in tin tubes. A sufficient quantity is pressed out on the center of the glass slide, which has previously been made thoroughly clean and dry, the insect is removed from the alcohol, and when the excess of liquor has been removed with bibulous paper, it is placed in the balsam, the limbs and antennae being arranged as desired by the use of fine mounting-needles. A cover-glass, also made thoroughly clean and dry, is then placed over the specimen and pressed gently until the balsam entirely fills the space between the cover and the glass slide. The slide should then be properly labeled with a number referring to the notes on the insect, preferably placed on the upper edge of the slide above the cover-glass, and also a label giving the number of the slide and the number of the slide box. On the opposite end of the slide may be placed the label giving the name of the specimen mounted and the date. If a revolving slide table is employed to center the mounts, the appearance of the slide may be improved by adding a circle of asphalt or Brunswick black. With the balsam mounts, however, this sealing is not necessary. The slide (Fig. 110) should then be placed in a slide case with the mount uppermost, and should be kept in a horizontal position to prevent sliding of the cover-glass and specimen until the balsam is thoroughly dried. For