102 PREPARATION AND MOUNTING 



be dissolved out of it ; it must then be soaked in water for tlie 

 same length of time, so as to soften and render it easy to cut. 

 Sections are obtained in the manner described above, but often 

 curl to such a degree as to make it necessary to immerse them in 

 water, from which they may be taken and dried under slight pres- 

 sure. They are often mounted dry, and require no care beyond 

 other objects, as in Chapter II. Some, however, are best mounted 

 in balsam, particularly the long sections when used for the pola- 

 riscope ; these must be soaked in turpentine, and the greatest 

 care taken that all air bubbles are got rid of. Others are thought 

 to be most useful when mounted in shallow cells with some of the 

 preservative liquids mentioned in Chapter IV. weak spirit and 

 water, chloride of calcium solution of the strength of one part of 

 the salt to three parts of distilled water, &c. 



The above "section-cutter" may not be within the reach of 

 every student, nor is it absolutely necessary ; though where any 

 great number of specimens is required it is very useful, and insures 

 greater uniformity in the thickness. Many employ a razor for the 

 purpose, which must always be kept sharp by frequent stropping. 

 Sections of leaves also may be procured by the same means, 

 though, as before mentioned, they are sometimes easily divided 

 by stripping the coatings off with the fingers. The cells which 

 come to sight by cutting some of the orchideous plants are most 

 interesting. To cut these leaves they may be laid upon a flat 

 piece of cork, thus exposing the razor to no danger of injury by 

 coming in contact with the support. It may be mentioned here 

 that the razor may also be used in cutting sections of the rush, 

 than which a more beautiful object can scarcely be found when 

 viewed transversely, as it shows the stellate arrangements of the 

 ducts to convey the liquids to the different parts of the plants very 

 clearly. This should be mounted dry. In the same way sections 

 of the leaf-stalks of ferns may also be cut, some of which, as Dr. 

 Carpenter states, show the curious ducts very beautifully, especially 

 when cut rather obliquely. 



When sections of the softer substances are required, no instru- 

 ment can be compared with " Valentin's knife," which consists of 

 two steel blades lying parallel with one another and attached at 

 the lower end. The distance of separation may be regulated at 



