1893.] MICROSCOPICAL JOURNAL. 317 



METHODS. 



1. Cut a slide 3 in. x 1 in. from the paste board. 



2. Apply lightly to each side of it a piece of adhesive plaster 

 3 in. long. 



3. Center the slide by drawing diagonal lines from the up- 

 per to the lower corners. 



4. Place the slide upon a block of hard wood and cut a disc 

 IVom its exact center by means of the punch or tiie cork borer. 



5. Coat the margins of the opening with Brunswick black. 



6. Strip the plaster from one surface of the slide so as to 

 full\' uncover the opening. 



7. Apply marine glue to the margin of a cover-glass, place 

 it over the opening on the uncovered surface of the slide and re- 

 place the plaster with firm pressure. 



8. Place the object in the cell. 



9. Instil the preservative or other medium. 



10. Strip the other surface of the slide, apply the second cover- 

 glass after the manner of the first and replace the plaster with 

 care. 



11. Apply ornamental back and front to slide, if desired. 



12. Label.' 



If the object to be mounted is an opaque one, apply but one 

 strip of the plaster before the opening is made in the slide. 



Then put the other strip in place so as to form a bottom to 

 the cell, which, together with the sides, is to be covered with 

 the Brunswick black. To finish, repeat the detnil- given above 



If the object is so minute as not to require a cell, place it oe- 

 tween two cover glasses with a pro|)er amount of Canada bal- 

 sam, clip and harden, mount in slides of thin paste board or of 

 metal having a central opening just large enough to receive the 

 covers and retain them with stripsof the plaster having an open- 

 ing 4 inch less than that of the slide. The metal slides of tin or 

 sheet iron should be ordered in quantity, ready for use, from a 

 dealer in hardware. If preferred, rings of the plaster, cut hy 

 means of circular label punches, may be used instead of strips 

 of the material. Court plaster has been recommended as a 

 mounting me lium, but the rubber plaster is superior to it for 

 the reason that it is used dry, that it is impervious to moisture, 

 that it adheres more firmly and does not crack. 



T^he rubber plaster may also be used upon glass slides. Cut 



