44 



HISTOLOGY OF MEDICINAL PLANTS 



The small size is designated three-fourths and the large 

 size seven-eighths. 



Cover glasses are circular (Fig. 41), square (Fig. 42), or 

 rectangular (Fig. 43) pieces of transparent glass used in covering 

 the specimens mounted on glass slides. A few years ago much 

 difficulty was experienced in obtaining uniformly thick and 



Fig. 41. — Round Fig. 42. — Square Fig. 43. — Rectangular Cover 



Cover Glass Cover Glass Glass 



transparent cover glasses, but no such difficulty is experienced 

 to-day. The type of cover glass used depends largely upon the 

 character of the specimen to be mounted. The square and 

 rectangular glasses are selected when a series of specimens are 

 to be mounted, but in mounting powdered drugs and histological 

 specimens the round cover glasses are preferable because they 

 are more sightly and more readily cleaned and rinsed. 



GLASS SLIDES 



Glass slides (Fig. 44) are rectangular pieces of transparent 

 glass used as a mounting surface for microscopic objects. The 



Fig. 44. — Glass Slide 



slides are usually three inches long by one inch wide, and they 

 should be composed of white glass, and they should have ground 



