22 THE ELEMENTS OF VEGETABLE HISTOLOGY 



Forceps. 



Glycerin jelly. 



Alcohol lamp or Bunsen burner. 



Operation: 



1. Arrange the requisite number of clean slides in regular order 



and attach temporary labels, or number with ink. 



2. Obtain specimen. These materials are usually preserved 



in a mixture of equal parts glycerin, alcohol and water. 



3. Cut a cube of glycerin jelly (§ inch) and place it near the 



specimen. 



4. Clean the needle by passing through the flame, remov'ng 



the carbonized material by wiping upon clean paper. 



5. Melt the cube of glycerin jelly by holding the slide a few 



inches above the flame. If mounting sections of plant 

 parts, allow the melted jelly to flow over the specimen 

 and proceed to step 6. If mounting powdered materials, 

 make an intimate mixture of melted jelly and specimen. 

 Cautions. — Keep the slide warm, use the point of the 

 needle for mixing; secure even mixture; keep mixture 

 within small area; use as little heat as possible; remember 

 that boiling causes formation of bubbles and spoils the 

 specimen. 



6. Pick up clean cover-slip with forceps and slightly warm it; 



allow it to touch the mixture of melted gelatin and speci- 

 men; withdraw the forceps, so that cover-slip gradually 

 comes into contact with entire mixture. If excessive 

 amounts of jelly have been used it will be necessary to 

 press gently on the cover-slip, forcing out the excess, so 

 that the mount will not be too thick for observation. 

 Cautions. — Do not track jelly on upper surface of cover- 

 slip; do not attempt removal of excess jelly at this time. 



7. Clean needle immediately, as directed in (4). 



After mounting specimens allow them to remain 

 flat until the jelly hardens. Excess jelly should not 

 be removed until a few days after mounting, as this 

 medium hardens slowly. To remove excess, scrape 

 off as much as possible with a knife and then 

 rub gently with silk or linen cloth moistened with 

 alcohol. 



