VASCULAR CYLINDER OR STELE I2\ 



that its effect is not so noticeable in these as in perennial woody 

 stems. 



Ex. 56. — Cut across the young soft stems of the sunflower, Jerusalem arti- 

 choke, groundsel, bean, potato, and any other common herbaceous plants. 

 Examine the cut surfaces with a pocket lens, and observe the presence and 

 arrangement of the vascular bundles and pith. 



Ex. B6. — Place some young sunflower stems in a mixture of two-parts methy- ' 

 lated spirit and one-part of water. Keep them in this mixture for further 

 use. From a stem which has been in the mixture three or four days cut 

 very thin transverse sections with a razor wetted with the mixture. Transfer 

 the sections to a watch glass containing water ; after remaining in the water 

 for a few minutes, take one out and mount it in a drop of water on a glass 

 slide. Cover with cover-slip and examine with the lowest power of the . 

 microscope. 



Make drawings indicating the position and general character of the 

 {a) epidermis, 

 {d) cortex, 

 {c) endodermis, 

 (rf) vascular bundles, 



and («) pith and mei'ullary ray tissue between the bundles. 



Examine with a high power, and make sketches of small portions of the 

 various parts above-mentioned, paying especial attention to the wood, 

 cambium and bast (compare Fig. 55). 



Try and see if the interfascicular cambium has been formed across the 

 medullary rays. 



Ex. 57. — Take a piece of sunflower stem about a quarter of an inch long, 

 preserved as in preceding exercise, and cut longitudinal sections so as to 

 pass through a vascular bundle. (In cutting longitudinal sections of stems, 

 the razor should cut from one side of the stem to the other, not from end 

 to end.) 



Examine first with a low and then with a high power : make sketches of 

 the form of the cells met with in the epidermis, cortex, bast, cambium, wood 

 and pith respectively. 



Try and determine which cells of the longitudinal section correspond with 

 those seen in the transverse sections. 



Ex. 58. — Make a careful study of the anatomy of a stem of groundsel, 

 bean, and other common herbaceous dicotyledons. 



Always begin the examination of sections with the lowest power at dis- 

 posal, namely, with the naked eye or a good pocket lens. After the general 

 arrangement of the chief tissues is understood, then apply higher powers in 

 succession. 



