390 Introduction to Botany. 



To seal the preparation in Canada balsam, remove the slide from the 

 dish of xylene and place it in a horizontal position. Place a small drop 

 of balsam to the left end of the group of sections. Grasp a thoroughly 

 clean and dry coverglass between the thumb and forefinger of the left 

 hand. Rest the lower edge of the coverglass on the slide close to the 

 drop of balsam, and lower it to the right over the sections. Support 

 the upper end of the coverglass by means of a dissecting needle held 

 in the right hand, and let the coverglass down slowly, so as to drive 

 all air bubbles forward and out from under it. During this process 

 keep the coverglass from sliding toward the left by means of a needle. 

 If the coverglass is of the oblong or square form it is often needful, 

 when it has nearly reached the horizontal position, to grasp its edges 

 by means of the thumb and middle finger of the left hand and press 

 it down against the slide with the tip of the forefinger, with a sliding 

 movement from the left toward the right end of the coverglass. In this 

 way the balsam, if scantily put on, is forced to the extreme edge of the 

 coverglass. 



The slide should now be kept at about 52° C. for several days to 

 harden the balsam. 



