384 Introduction to Botany. 



spread out, the slip has not been thoroughly cleaned. It is a good 

 plan to keep the slips in concentrated sulphuric acid saturated with 

 bichromate of potash contained in a pint Mason jar, and then to rinse 

 and polish them as needed. The albumen water is made as needed 

 from a stock solution. To make the stock solution, shake together 

 equal parts of the white of one egg and glycerine, and add to this mix- 

 ture a small amount of salicylate of soda to keep it from spoiling. Allow 

 the mixture to stand over night in a tall cylinder, and skim off the im- 

 purities which rise to the top. To make the albumen water, add i 

 drop of the stock solution to about 10 cubic centimeters of distilled 

 water. Make the albumen water afresh every few days, as the old 

 solution becomes turbid or is found to contain a precipitate. 



Having spread the albumen water on the glass slip, cut a piece of the 

 desired length from the ribbon of sections and lay it upon the albumen 

 water, and so on until nearly the entire breadth of the slip is occupied, 

 in case rectangular coverglasses are used and it is desired to study the 

 sections in series in the order in which they were cut. With a piece of 

 filter paper filter away most of the albumen water, and while doing it 

 arrange the sections at the center of the slip. Then place the slip to 

 dry on the copper plate of the paraffin imbedding apparatus described 

 under Imbedding in Paraffin. Place asbestos paper or felt paper be- 

 tween the slip and the copper plate until the slip is heated to a little 

 below the melting point of the paraffin. It is best to let the slips 

 remain thus for an hour or more. 



Before staining the sections stand the slide on end in a tumbler of 

 xylene to dissolve the paraffin. (After the sections have been mounted 

 on the slip it is the custom to call the entire preparation a slide.) The 

 sections should adhere to the slip during this and all subsequent manipu- 

 lations. Rinse off the xylene in a tumbler of 95 % alcohol and stain the 

 sections as directed under Staining and Sealing in Balsam. 



Cyanin and Erythrosin for Double Staining. — Sections of plant 

 tissues having both cellulose and lignified walls may be double stained 

 in the following manner: Place the sections for a few hours or over 

 night in a saturated solution of cyanin in 95% alcohol; then rinse the 

 sections in a dish of 95 % alcohol until the cyanin ceases being washed 

 out in clouds. (This should be within a few moments.) Then trans- 

 fer the sections to a saturated solution of erythrosin in clove oil. Leave 

 them there only a moment and then place them in a dish of xylene and 

 mount almost immediately in Canada balsam as described under Stain- 



