THE STEM 59 
a longitudinal section passing through a vascular bundle. 
Make out and sketch— 
(a) Epidermis ; 
(b) Cortex aud endodermis with starch grains ; 
(c) Pericycle fibres ; 
(d) Phloem (parenchyma, companion cells and sieve tubes) ; 
(e) Cambium ; 
(f) Xylem with pitted and spiral vessels ; 
(g) Pith. 
6. Cut a transverse section on an oak twig of the current 
year. Make out the parts enumerated in 4, and compare the 
two sections. 
7. Cut the stem of a young oak seedling transversely. 
Note that the bundles do not yet form a complete ring. 
8. Cut the stem of a three-year-old oak transversely with a 
sharp knife. Examine with a lens. Note the annual rings 
and the medullary rays. 
9. Cut transverse sections of the bark of an oak stem. 
Examine under the low power and make out— 
(a) Phloem ; 
(b) Groups of sclerenchyma ; 
(c) Primary cortex ; 
(d) Cork cambium and cork cells and phelloderm or 
secondary cortex. 
Also cut longitudinal sections of same and make out the 
same tissues. 
10. Cut a transverse section through an apple twig, cutting 
across a lenticel. Examine under the low power, and sketch— 
(a) The ruptured epidermis ; 
(b) The loose cork cells ; 
(c) The cork cambium. 
QUESTIONS ON CHAPTER IV. 
1. Make a diagrammatic sketch to show the structure of 
the stem of asunflower, as seen in transverse section. Describe 
the functions of the different tissues of the vascular bundle, 
and make drawings to show the form of a characteristic cell 
from each tissue, 
