THE LEAF 155 
coloring fluid a short time before the lesson begins. The leafstalks of 
celery and plantain are excellent for showing the relation between the leaf 
veins and vascular system of the plant. 
171. Parallel and net veining. — Compare a leaf of the 
wandering Jew, lily, or any kind of grass, with one of grape, 
ivy, or willow. Hold each up to the light, 
and note the veins or little threads of woody 
substance that run through it. Make a draw- 
ing of each so as to show plainly the direc- 
tion and manner of veining. Write under the 
first, parallel-veined, and under the second, 
net-veined. This distinction of leaves into 
parallel and net-veined cor- 
responds with the two great 
classes into which seed-bear- 
ing plants are divided, mon- 
ocotyls, as a general thing,  wyo. 205, — Par- 
being characterized by the @llel-veined leaf of 
first kind, and dicotyls by Ge Oia: aad 
the second. 
172. Pinnate and palmate veining. — 
Fie. 206.—Net- Next, compare a leaf of the canna, calla lily, 
= leaf of » wil- or any kind of arum, with one of the elm, 
peach, cherry, etc. What resemblances do 
you notice between the two? What differ- 
ences? Which is parallel-veined and which 
is net-veined? Make a drawing of each, and 
compare with the first two. Notice that in 
leaves of this kind, the petiole is continued 
in a large central vein, called the midrib, 
from which the secondary veins branch off 
on either side like the pinne of a feather; 
whence such leaves are said to be pinnately, 
or feather veined, as in Figs. 206, 207. In ay, 207, Pin- 
the cotton, maple, ivy, etc., on the other ately _ parallel- 
veined leaf of calla 
hand, the petiole breaks up at the base of the tity (After Grav). 
