TOOLS AND METHODS OF WORK 



23 



sections are being cut, but its consistency may be modified by the 

 addition of a little vaseline, and is much improved by constant and 

 repeated use. There is no other medium required for imbedding 

 ordinary roots and stems, and many of the leaves, seeds, &c., even the 

 cellular aquatic roots and stems are imbedded for cutting in this way. 

 The specimen is taken out of the stock jar, placed in jDosition in the 

 well of the microtome, and held in position with a needle while the 

 melted paraffin is being poured in. After the "candle" so formed is 

 set hard, the superfluous paraffin is removed from the knife-plate with 

 an old section knife, which completes the operations preparatory to 



section-cuttmg. 



Preparing Specimens for Sectiomsing. 



Most of the delicate tissues and all specimens having loose parts 

 require some special method of treatment before they can be sectionised 

 with success. The methods best adapted for this purpose are the 



-ffl-- 



V7 



Fig. 15. — Diagram showing the various positions of floral parts in a lily, the dotted line 

 being the line of cut for celloidinising purposes. 



