102 MKIUSTKM TISM'E. 



trilateral pyramidal cell with its convex base turned toward 

 the root-cap, the apical cell. 



3. A transverse partition cutting off the outermost portion, 

 which becomes the initial cell of the root cap, Dermatogen. 



4. Segments cut from the innermost faces of the cell and, by 

 longitudinal partition, developing into the tissues of the Pler<>nn> 

 uinl r< riblem. 



Strasburger, p. 188 ; Vines' Text Book of Bot, p. 150 ; De- 

 Bary, p. 18. 



In the transection, OBSERVE : 1. The irregularly thickened 

 walls of the epidermic. 



2. The cortex consisting, on the peripherial portion, of dark 

 brown parenchyma and merging into sclerenchyma toward the 

 plerome. 



3. The bundle sheath between the cortex 'and fibro-vacular 

 bundle. 



4. The pericambium, a narrow sheath ( just inside the bun- 

 dle sheath) of parenchyma cells filled with protoplasm. 



5. The regular radial bundle of the root. 



If time will admit a comparative study should be made of the 

 apex of the stems of Monocots, Dicots, and higher Cryptogams. 



The preparation of the tissues for study would be the same as 

 that recommended for the roots. DeBary, p. 19 ; Strasburger, p. 

 177 ; Vines' Text Book of Bot., p. 146. 



Fibro=Vacular Bundles. 



The following general classes are noted : 



A. Collateral. 



B. Bicollateral. 



C. Radial. 



D. Concentric. 



Illustration A : Stem of BEGONIA, GERANIUM, MOON SEED 

 Vine, or SMILAX. 



PREPARATION FIRST: The herbaceous stems should be pre- 

 pared in the usual way, the woody ones may be sectioned by plac- 

 ing them between pieces of cork in the jaws of a microtome. 

 Transaction and longisection should be mounted together. 



