92 ELEMENTS OF BOTANY. 
the midrib (in pinnately veined ones). Such divided leaves 
are shown in Figs. 69,and 70. 
In still other leaves, known as compound leaves, the petiole, 
as shown in Fig. 75, or the midrib, as shown in Fig. 76, bears 
what look to be separate leaves. These differ in their nature 
and mode of origin from the portions of the blade of a 
divided leaf. One result of this difference appears in the fact 
Fa. 75. — The Fall of the Horse-Chestnut Leaf. 
that some time before the whole leaf is ready to fall from the 
tree or other plant in autumn, the separate portions or leaflets 
of a compound leaf are seen to be jointed at their attachments, 
just as whole leaves are to the part of the stem from which 
they grow. In Fig. 75 the horse-chestnut leaf is shown 
at the time of falling, with some of the leaflets already 
disjointed. . 
