68 



BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



25 slides. Others lay the slides on sliding shelves of a large box 

 or case. 



Mr. Marlatt has perfected a way of keeping slides on the card sys- 

 tem which is superior to all other methods. Each slide is put in a 

 small manila envelope or jacket (fig. 112), expressly made for this 

 purpose, and these placed on edge as cards in a tray. The cabinet, 

 holding several trays each, with three rows, is made by dealers in 

 library supplies. On the outside of the envelope may be written 

 the name and locality of the specimen or other information. Guide 



Fig. 113.— A case for storing specimens mounted on microscope slides. 



cards, with the name, of the species or the genus, may be used to 

 separate the series. By this method one may insert new slides or 

 new species at any time in their proper places, and all are secure 

 from dust. One must be careful that the balsam is fully dried before 

 putting the slides in these jackets. 



Most of the wingless insects are best studied when mounted on 

 these slides, as also larval and immature stages of other insects, and 

 the sections of mouth-parts, etc. For studying the general structure 

 more elaborate methods are required, which may be learned from a 

 number of books on microscopical and histological technique. 



