PRACTICAL STUDY. 113 



7. Prepare thin longitudinal sections of the mature rhizome, 

 imbedding in celloidin or between pieces of pith, according to in- 

 structions by the demonstrator (see Appendix). Stain some of 

 them in iodine, and others in aniline chloride as before. Mount 

 a number of sections in dilute glycerine, and study carefully, 

 comparing with the cross-sections. Make out the three systems, 

 and the constituent tissues and cells. 



8. Repeat the foregoing observations with thin, longitudinal 

 sections passing through an apical bud. 



i 



D. Meristem. Apical Cell. Differentiation. 



1. In good sections prepared as in C. 8, observe 



a. The general shape of the bud, the funnel-shaped pit at 



the extremity, and the hairs which cover it. 

 5. Search for the apical cell, comparing Figs. 42-44. 



c. Notice the undifferentiated condition of the tissue 



(meristem) at the extremity, its richness in proto- 

 plasm, and the progressive differentiation behind 

 the apical cell. 



d. Repeat these studies upon transverse section, sketching 



especially the developing cells of sclerotic prosen- 

 chyma and the tracheids. 



e. Stain a number of sections with borax carmine, iodine 



solution, aniline chloride, cosine and methyl green, 

 and compare carefully 



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E. Histology of the Aerial Parts. 



1. THE STIPE. 



Study transverse and longitudinal sections of the stipe. 

 Sketch. 



2. THE LAMINA. 



a. Moisten a leaflet with water, scrape lightly the upper 



surface, and mount in water the transparent colorless 

 bits of epidermis thus peeled off. Sketch. 



b. Stain with iodine, and report your results. 



c. Scrape and examine the lower surface as in (a). Be 



careful to get only colorless bits. Study, then stain 

 with iodine and sketch. In the stomata notice espe- 

 cially the guard-cells, their contents, and the chink 

 (stoma). 

 8 



