204 



THE MICROSCOPE. 



With a little practice tlie finest and thinnest possible 

 slices will be cut. It is usual to first slice off a few 

 thicker slices to give a smooth and even surface to the 

 specimen. Then turn the screw to raise it a little, 

 sprinkle the surface with spirit and water, and cut 

 with a light hand. Remove the cut sections with a 

 fine camel's-hair brush or blotting-paper to a small 

 vessel containing water, when the thinnest sections 

 will float on the surface, and are more easily selected 

 and removed to a bottle of spirit and water, where 

 they should remain until they can be mounted. Sec- 

 tions of hard woods, and of those containing gum, 

 resin, and other insoluble materials, must first be soaked 

 in alcohol or ether and then transferred to oil of cloves, 

 to render them sufficiently transparent for mounting. 



I 



FIG. 143a. Sections of Wood. 



If the entire structure of any exogenous wood is 

 required to be examined, the sections must be made in 

 at least three different ways : these may be termed the 

 transverse, the longitudinal, and the oblique, or, as 

 they are sometimes called, the horizontal, vertical, 

 and tangental : each of these will exhibit different 

 appearances, as may be seen upon reference to fig. 143# : 

 6 is a vertical section through the pith of a coniferous 

 plant : this exhibits the medullary rays, which are known 



