103 MKH1STKM YV.s.srf;. 



In the preparation of the Moon Seed Vine, (M<'ni.-<i>< 

 Canadense) a stem of one year's growth should be selected. 

 (Fig. 27.) 



Examine with a hand lens, and observe the general manage- 

 ment of the tissue systems in a cross-section. 



1. Pith, (Fundamental Tissue.) 



2. Fibro-vascular bundles, (outline of each is nearly circular). 



3. Epidermis. 



OBSERVE : 1. The Epidermis; The external walls of its cells 

 being thickened very greatly, and a light olive in color, the inner 

 and lateral walls being of ordinary thickness and the cell cavity 

 small. 



2. The Cortical Parenchyma; of two kinds of cells, both 

 containing chlorophyll. 



(a) The outer are regular, closely packed and thick-walled. 



(b) The inner are thinner-walled, larger and looser, passing 

 into the oblong cells of the Medullary Rays. 



3. The Fibro - Vascular Bundles : 



The Phloem is sharply distinguished from the Xylem, form- 

 ing a strictly Collateral Bundle. 

 In the Phloem : 



(a) The Crescent -/Shaped band, of thick-walled cells on the 

 peripheral side of the Phloem ; the lamellate structure of the walls. 



(b) The squarish outline of Phloem cells adjoining the thick- 

 walled Xylem. Some of them somewhat thickened (lignified). 



(c) The larger cells lying between (a) and (b). They are 

 irregular in outline, thin-walled and stain but slightly. 



In the Xylem: 



(d) The larger duct openings between which the smaller cells 

 (tracheids, etc.,) appear. 



(e) The thick-walled cells of the axial region of the xylem 

 forming a continuous band, or "bundle sheath," bounding the axial 

 side of the fibre-vascular bundles. 



(f) Between the A'///< //> and Phloem several of narrow, thin- 

 walled cells the Cambium. This is the region of growth, in sec- 

 ondary thickenings. 



In the radial-loncjitudinal sections trace out the groups of 



