Ch. X.] APPENDAGES TO PLANTS. 61 
found upon the leaf or the calyx, and in some instances upon the 
berry ; as in the Gooseberry. 
Fig. 39. 
~ 243. Thorns, seem to be a kind of short pointed stem, easily 
distinguished from prickles, as they grow from the woody part 
of the plant, while the prickle proceeds only from the bark. On 
stripping the bark from a rose-bush, the prickles will come away 
with it, but let the sane experiment be made with a thorn bush, 
and although the bark may be separated, the thorn will still re- 
main projecting from the wood. 
4 244. In this drawing (Fig. 39) you will observe the thorn (a) 
_to remain on the stem, while the bark (6) has been peeled off. 
In the prickle (c) the whole appears separated from the plant. 
Thorns in some plants have been known to disappear by culti- 
vation. The great Linneus imagined that the trees were di- 
vested of their natural ferocity and became tame. A more ra- 
tional opinion is given by another botanist, viz.: that thorns are 
in reality buds, which a more favourable situation converts into 
luxuriant branches. But in some cases they do not disappear 
even-under circumstances favourable to vegetation. Thorns 
have been compared to the horns of animals. 
245. Glands are roundish, minute appendages, sometimes 
called tumours or swellings; they contain a liquid secretion, 
which is supposed to give to many plants their fragrance.— 
They are sometimes attached to the base of the leaf, sometimes 
they occur in the substance of leaves; as in the Lemon and 
Myrtle, causing them to appear dotted when held to the light. 
They are found on the petioles of many plants, and between 
the teeth or notches of many others. 
246. Stings are hair-like substances, causing pain by an 
acrid liquor, which is discharged upon their being compressed ; 
they are hollow, slender, and pointed, as in the Nettle. 
247. Scales are substances in some respects resembling the 
243. What are thorns? 
244. ‘What does Fig. 39 represent? 
245. What are glands? 
246. What are stings ? 
247. What are scales? 
5 
