102 



PRACTICAL COURSE IN BOTANY 



r u 



Fig. 118.— Side 

 view of the sieve 

 tube of a gourd stem : 

 pr, protoplasm layer ; 

 u, albuminous con- 

 tents, forming muci- 

 laginous strand. 



the cell wall by osmosis? [56 (4).] The 

 conducting cells are surrounded by a mass 

 of strengthening fibers separating them 

 from the parenchyma,/, and constituting 

 with them a fibrovascular bundle. The 

 larger vessels, m, m' , a, and sjj, compose 

 the xylem, the harder, more woody part 

 of the bundle, and the smaller ones, v, s, 

 the phloem, or softer part. Notice also 

 that there is no parenchyma in contact 

 with the xylem and phloem in the fibro- 

 vascular bundles of a monocotyl, to supply 

 material for new growth, but they are 

 entirely surrounded by a sheath of strength- 

 ening tissue, whence such bundles are said 

 to be closed, and are incapable of further 

 growth by the addition of new cells. 



B. Herbaceous Dicotyls 



Material. — Young stems of sunflower, hollyhock, burdock, ragweed, 

 cocklebur, castor bean, or any large herbaceous plant. In schools un- 

 provided with compound microscopes, the minute anatomy can be studied 

 with some degree of profit by the aid of pictures. 



115. Gross anatomy. — Examine the outside of a young 

 stem of sunflower, burdock, or other herbaceous dicotyl. 

 Notice whether it is smooth, or roughened with hairs, scales, 

 ridges, or grooves. If hairy, observe the nature of the hairs, 

 whether bristly, downy, sticky, etc. Notice the color of the 

 epidermis, whether uniform, or splotched or striped with 

 other colors, as, for example, jimson weed, and pigweed 

 (amarantus). If there are any buds, branches, or flower 

 stems, notice where they originate ; what is the angle be- 

 tween the leaf and stem called? (100.) 



Make a transverse cut through a portion of the stem that 

 has stood for a time in coloring fluid and examine with a lens. 

 Four regions can easily be distinguished : (1) the epidermis, 



