121 



sary first to remove all water by either (a) drying Desiccation, or 

 (d) a series of displacements, i.e., i. Removing the water with 

 strong alcohol Dehydration; 2. Removing the alcohol with 

 clearer Clearing ; 3. Replacing the clearer with balsam or other 

 resinous mounting medium. 



10 1. Temporary mounting. Used in this course princi- 

 pally in the examination of blood corpuscles and living ciliated cells 

 (2). Temporary examination of tissues is quite simple, though 

 important, and for this it is only necessary to place the teased tissue 

 or section on the slide in a drop of the fluid in which it is at the 

 time, normal salt solution, dissociator, or alcohol, and cover. The 

 examination of preparations intended for permanent mounts during 

 the staining or before mounting will often serve to detect faulty 

 treatment at a time when it may be remedied without great expend- 

 iture of time, or discard the specimen as worthless. 



102. Permanent mounting. In this course are employed 

 () mounting dry on a ring or in a cell, () in glycerin or glycerin 

 jelly, media miscible with water, and (c^) in xylene balsam, a resin- 

 ous medium. 



103. Mounting dry. The preparation may be either upon 

 the under side of the cover-glass (best if possible) or rest upon the 

 bottom of the cell. 



In the first case a shallow cell made by a shellac ring will be 

 sufficient ; in the second, a shellac ring may not give a deep enough 

 cell and a paper, hard rubber, or metal ring may be cemented to the 



slide. 



(a) When the preparation is on the cover. Prepare a shellac 



cell ( 1 06) on the slide of a size slightly smaller than the cover to 

 be used, and allow it to dry for a day or so. Warm the cover bear- 

 ing the preparation to remove the last traces of moistuie, and place 

 it film side down upon the ring. Warm the slide until the edge of 

 the cover may be made to adhere to the shellac ring and press the 

 cover down until it adheres all the way round. Seal the cover with 

 shellac and label ( in, 113). 



(b) Mounting in a paper or rubber cell. With a brush, cover 

 one side of the ring with a layer of shellac and place it on the center 

 of the slide, shellac side down ; place within the cell the prepara- 

 tion, arranging it in the manner desired, and place upon the ring a 

 cover-glass of a suitable size, and seal it with shellac ; label. 



