DICOTYLEDONOUS Zh 
Select a short piece of stem one year old; split it in 
half, and cut Icngitudinal sections from the split surface. 
Study these sections carefully, with the low and high 
power and identify all the different kinds of cells seen in 
the cross sections by referring to their relative position. 
Many of the vessels have elongated pits running trans- 
versely in their walls. Bast fibers and medullary ray 
cells will not be found in every section. Why not? The 
medullary ray cells appear somewhat like brick-work. In 
connection with your longitudinal sections study macer- 
ated tissue, which the instructor will prepare for you. 
In macerated tissue a side view of the fibers and vessels 
will be seen. This is, of course, much like the view ob- 
tained in long. sections. Draw three or four cells of each 
different kind of tissue found in longitudinal sections ex- 
cepting fibers and vessels. Make a detailed drawing of 
a portion of a wood fiber, a bast fiber, and a vessel as seen 
in macerated tissue, and another outline drawing of a 
few adjoining cells of each kind showing how they are 
united. 
Exp. 18: Place the cut end of an elder and a beech 
twig containing several leaves into a weak solution of 
eosin, also the proximal end of a rather long potato with 
a little of both ends cut off. After 24 hours make cross 
and longitudinal sections of the stems with a scalpel. 
Study these sections, the cut surfaces, and also the leaves. 
What conclusions can you draw? Do you find any 
woody tissue in the potato; any vessels; bark; pith? 
Razor sections may prove advantageous in studying the 
potato. 
