14 APPARATUS AND METHODS. 



the pith to crack, lay the pith on the table, hold it be- 

 tween thumb and fingers, and cut it in halves with a sharp 

 knife do not use your section- cut ting razors for any 

 rough work like this. With the knife, cut a groove in the 

 pith so that the stem or root, etc., may be placed securely 

 in position and held firmly, yet not so tightly as to com- 

 press the tissues much. In the case of a leaf, simply hold 

 a strip of the leaf between the two halves of pith. 



Having placed the specimen in position between the two 

 pieces of pith, treat the whole as if it were a piece of solid 

 tissue like a stem. Trim off the end and cut thin sections 

 from it, judging the thickness of each section of the 

 specimen by the opacity or transparency of the pith 

 sections cut along with it. Cut a good number of sections, 

 transfer them to weak alcohol in a wa,tch-glass or saucer, 

 and pick out the sections of the specimen for further 

 treatment. 



With the exercise of patience and ingenuity in the 

 making of suitable grooves and other excavations for the 

 reception of the specimens to be cut in pith, extremely 

 good results may be obtained. 



12. Mounting. In the following directions the term 

 "specimen" applies to all objects examined, whether entire 

 or in thin sections. 



First, see that the slide and cover- glass are dry and 

 clean. Take a slide by its edges with thumb and fore- 

 finger of left hand, dip one half of it in water, withdraw 

 it, and with a clean cloth (an old handkerchief is better 

 than a duster, being freer from fluff) rub both wetted 

 surfaces at once until they are quite clean and dry ; then 

 lay the slide on a clean suitable background, as white or 

 black paper. 



Cover-glasses, as bought from dealers, often have a 

 cloudy film on them ; to get rid of this, put the cover-glass 

 in 50 per cent, sulphuric acid for a minute, then rinse 

 it in water ; take it between two folds of the cloth held 

 between thumb and forefinger of right hand, and carefully 

 rub both surfaces at once until clean and dry ; do not lay 



