276 AUTUMNAL LEAVES. 



stem. Upon the base and upon that part of each 

 side of each leaflet next the base, there are no 

 indentations. But the remainder of the edge is 

 so sharply incised that the points of the serratures 

 resemble spines or bristles. The mid- vein divides 

 each leaflet into about two equal parts, and from 

 it proceed, in alternation to each margin, a series 

 of waved branch veins, a branch vein running to 

 the point of each of the marginal spines. It is 

 interesting to note, in the venation of leaves, that 

 the principal branch veins which run through the 

 tissue from the mid-vein to the margin sometimes 

 run to the points of the segments, into which the 

 margin is cut, and sometimes to the base of the 

 crenatures ; and that whilst sometimes, and more 

 frequently, a separate branch vein will run direct 

 from the mid- vein to the bases or apices of the 

 serratures, at other times one principal branch 

 vein will, by forking near the margin, run to two 

 of the divisions into which the margin is cut. 

 The network of veinlets which traverse the tissue 

 of the Mountain Ash leaf, between the lines 

 formed by the principal veins, is very elaborate 

 and beautiful. 



