98 Modern Microscopy. 



The following specimens from the vegetable kingdom 

 make fine polariscope objects : Starches, hairs, scales from 

 leaves, cotton and silk fibres, cuticles of leaves, and longi- 

 tudinal and transverse sections of stems. 



Starches can be obtained from any vegetable substance 

 by scraping the tissue with a knife. Place the scraping in 

 a test-tube of water and shake well ; allow the starch to 

 settle down, and pour off the water. Kepeat the washing 

 until all the fibrous material is washed away. For polarizing 

 purposes starches should be mounted in Canada balsam. 

 Take up a little starch in a dipping-tube, and place it on a 

 cover-glass ; dry slowly, apply a drop or two of balsam, 

 and mount in the usual way. Starches may also be mounted 

 in glycerine jelly. 



Cuticles containing Raphides. The most common is 

 the skin of the onion. Strip off the cuticle, soak in turpen- 

 tine for a few days, or until transparent, and mount in 

 Canada balsam. 



Cuticles may also be mounted in glycerine jelly. 



The following specimens of the animal kingdom make 

 good objects : Fish-scales, palates of mollusca, sections of 

 hairs and quills, horns and hoofs, whalebone, etc. 



Fish-scales. Scrape off the scales, and wash well in 

 water if very dirty ; soak in liq. potassse for a day or two, 

 and wash again in water. Pour off the water and add 

 methylated spirit, and soak for an hour, or until required. 

 Place in clove oil, and soak for several hours until quite 

 free of air. Mount in Canada balsam. 



Palates. Dissect out, and soak in liq. potassse for a few 

 days. Wash well in water, spread out on a slide ; put a 

 piece of paper on each side of it to prevent crushing, and 

 place another slide over all in the same way as directed for 

 insects ; tie the glasses together with string, and place in 

 methylated spirit for an hour or two. Then remove the 

 palate from the glasses, and place it in clove oil until 

 clear. Mount in Canada balsam. 



