BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [84] 



than tlie use of any of tlie chemical wax solvents which we have tried." 

 {Insect Life, 1, i). 152.) 



Mounting Specimeiis 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 i^reparation 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 knowl- 

 edge 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 pre- 

 viously 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 sj)ace 

 between the cover and the glass slide. The slide should then be prop- 

 erly labeled with a number referring to the notes on the insect, prefera- 

 bly 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 slidiug of the 

 cover-glass and specimen until the balsam is thoroughly dried. For 

 storing slides I have found very convenient the box shown at Fig. 



