16 THE CELL WALL 



4. Draw several connected wood-parenchyma or wood-ray 

 cells from the macerated xylem of Tecoma radicans, showing 

 clearly the size, structure and arrangement of the simple pit-pairs 

 as seen in both face and sectional view. Label the following : 

 compotmd middle lamella, secondary wall, pit aperture, pit cav- 

 ity and pit membrane. 



5. Draw, on a large scale, a single tracheid from macerated 

 pine xylem, showing the form and arrangement of all pits (bor- 

 dered and simple) as seen in face view. Label carefully. Pre- 

 pare drawings based on the study of the longisections of pine 

 wood showing sectioned vieivs of bordered pit-pairs as well as the 

 type of pitting between tracheids and wood rays. In these draw- 

 ings label the following: compounel middle lamella, secondary 

 wall, border of pit, aperture of pit, cavity of pit, pit membrane, 

 torus and crassidae. 



6. Prepare drawings, based upon the study of macerated and 

 sectioned wood and bast fibers of Platanus and Tiliu, shoAving the 

 arrangement and structure of vestigial pit-pairs in both face and 

 sectional views. 



REFERENCES 



1. Anderson. D. B., The Structure of the Walls of tlio Higher 

 Plants. Bot. Rev. 1 :52-76. 1935. 



2. Bailey, I. W., and Kerr, T., The Visil)lo Structure of the Sec- 

 ondary Wall and Its Significance in Physical and Chemical 

 Investigations of Tracheary Cells and Fibers. Jour. Arnold. 

 Arb. 16:273-800. 1935. 



3. Bonner, J., The Chomistrv and IMn'siolotrv of the Pectins. 

 Bot. Rev. 2:475-497. 1936". 



4. Crafts, A. S. A Tecimic for dciuonstrating plasmodesmata. 

 Stain Technology 4:127-129. 1931. 



5. Eames and Mac Daniels, Ch. IT. i^p. 19-38. 



6. Frost, F. II., Histology of the Wood of Angiosperms, I. The 

 nature of the jutting between trachearv and parenchvmatous 

 cIciiuMils. r.iill. T(invy P.ot. Club. 56:259-264. 19i29. 



7. liaberhindl, Ch. I. pp. 43-50; Ch. XIII, pp. 635-638. 



8. llavward, Ch. 1, pp. 5-11. 



9. Jeffrey, Ch. I. 



