92 POWDERED VEGETABLE DRUGS 



4. Vascular Tissue. The endoderm cells may prove diagnostic 

 (varieties of sarsaparilla) . They should be carefully examined as to 

 the size and form of the cells, thickness and uniformity of thickness 

 of the cell-walls, porosity and color of cell-walls and nature of cell- 

 contents. The ducts will frequently prove diagnostic. Study them 

 as to size (diameter), form of thickenings (porous, scalariform, rectic- 

 ulate, spiral, annular). The bast and wood elements accompanying 

 the vascular bundles vary in quantity. Sieve tissue, conducting cells, 

 and meristematic tissues are rarely diagnostic. The parenchyma of 

 the vascular bundle is, in most respects, similar to other parenchyma. 

 Tracheids may prove diagnostic. Study them carefully as to size, 

 number and form of pores, etc. In some instances the abundance of 

 tracheids and wood elements will prove diagnostic. Note carefully 

 the form, grouping and contents of the cells of the medullary rays. 



5. Laticiferous Duels. These occur in a number of vegetable drugs 

 and will be of considerable diagnostic value to the careful observer. 



6. Pith. This is usually deficient and of little diagnostic value. 

 The cells are usually thin- walled, typically parenchymatous and pretty 

 well broken in powders. Note porosity of walls and absence or presence 

 of crystals and resin. 



6. STEMS 



There are only comparatively few medicinal stems. They are 

 mostly quite woody, and some, as coniferous stems, have the leaves 

 included. 



1. Epidermal Elements. Usually present, and should be carefully 

 compared with those of leaves. As a rule, they are less abundant and 

 less characteristic. 



2. Hypoderm. Usually of no significance (see Leaf). - 



3. Chlorophyll-bearing Parenchyma. This may be present, but is 

 rarely diagnostic. 



4. Collenchyma. When quite abundant and typically developed 

 it will prove quite diagnostic, but it is only the transverse view of long 

 cells which will present the characteristic appearance of these elements. 



5. Bast. See " Roots and Rhizomes." 



6. Parenchyma. Cell-contents less abundant and usually less 

 characteristic or diagnostic (see Roots and Rhizomes). 



7. Woody Tissue. This is usually very abundant and diagnostic. 

 Note length, diameter and porosity of elements. Note medullary 

 rays and cell-contents. 



8. Sclerenchyma. Not generally present (see Barks). 



