516 PRACTICAL BOTANY 



sections must be well washed in distilled water, and then placed 

 in a small quantity (1 c.c.) of the saturated alcoholic solution 

 mixed with an equal volume of distilled water ; they require to 

 be left for several hours in the staining fluid. They must then 

 be removed, and washed for a short time in alcohol ; then they 

 must be placed in absolute alcohol, and kept there until they 

 appear transparent. The sections can now be mounted in dis- 

 tilled water in order to see if the results are satisfactory, or, if 

 they are to be preserved, they must be cleared with oil of cloves, 

 and mounted in Canada balsam or Dammar. 



By this means very successful preparations of the structure of 

 nuclei can be obtained. 



Schulze's Macerating Fluid. One gramme of potassium 

 chlorate is dissolved in 50 c.c. of nitric acid ; or crystals of potas- 

 sium chlorate may be left to dissolve to saturation in a small 

 bottle of nitric acid. This reagent is to be used only in small 

 quantities, and the process of maceration should not be conducted 

 in near proximity to microscopes, or other metallic apparatus. 



It is used as a macerating fluid for separating the constituents 

 of woody tissues from one another, this result being obtained by 

 the solution of the middle lamella. The tissue to be macerated 

 is cut into small chips, and boiled in the fluid for a short time in 

 a test-tube ; the fluid is then poured off and the residue collected 

 on a filter, and well washed with water : the specimens may then 

 be mounted in glycerine (see p. 104). 



Schulze's Solution (see above, Chlor-Zinc-Iodine). 



Sodium Chloride is used as a 10 per cent, solution, or as a 

 saturated solution in water, as a solvent for proteid-crystalloids 

 (see Appendix B). 



A more dilute solution (1-5 per cent.) is used for inducing 

 plasmolysis (see pp. 26, 31, &c.). 



Sulphuric Acid. This is used either concentrated, or dilute 

 (1 to 3 of water). It causes, in either case, the swelling up of 

 cellulose cell- walls, starch-grains, &c. (p. 46) ; when cellulose 

 cell- walls which have been previously saturated with solution of 

 iodine are treated with sulphuric acid, they turn blue (p. 36). 



Concentrated sulphuric acid dissolves cellulose and starch, but 

 cuticularized or corky cell-walls and the middle lamella of ligni- 



