THE ROOT 61 
Practical Questions 
1. Could any normal plant grow in a soil from which nitrogen was lack- 
ing? Potash? Lime? Phosphorus? (62.) 
2. Could it live in an atmosphere devoid of oxygen? Nitrogen? Car- 
bon dioxide? (62.) 
3. Why are cow peas or other legumes planted on worn-out soil to renew 
it? (63.) 
4. Is the same kind of fertilizer equally good for all kinds of soil? For 
all kinds of plants? (60, 62.) 
5. Why does too much watering interfere with the nourishment of 
plants? (Exps. 26, 27.) 
6. Are ashes fit for fertilizers after being leached for lye? (62.) 
7. Why will plants die, or make very slow growth, in pots, unless the 
soil is renewed occasionally? (60, 62.) 
II. STRUCTURE OF THE ROOT 
Marteriau. — Taproot of a young woody plant not over one or two 
years old; apple and cherry shoots make good specimens. For showing 
root hairs, seedlings of radish, turnip, or oat are good, also roots of wan- 
dering Jew grown in water; for the rootcap, corn, sunflower, squash. 
64. Gross anatomy of the root. — Cut a cross section of 
any woody taproot, about halfway between the tip and the 
ground level, examine it with a lens, and sketch. Label 
the dark outer covering, epidermis, the soft layer just within 
that, cortex, the hard, woody axis 
that you find in the center, vas- 
cular cylinder, and the fine sil- 
very lines that radiate from the 
center to the cortex, medullary 
rays (in a very young root these 
will not appear). Cut a section 
through a root that has stood in 
coloring fluid for about three 
hours and note the parts colored / } 
by the Fuld) Wnt nomen oF Ee ae 
the root, would you judge from mis; ¢c, cortical layer ; d, fibrovascular 
this, acts as a conductor of the cylinder. Note the absence of med- 
ullary rays during the first year of 
water absorbed fromthe ground? growth. 
