LXVI OUTLINES OF BOTANY. 
’ 
— filled with starch or other substances (192). There i s seldom 
fi : 
ieee e often very indistinct or have no relations to seasons of 
i 8 
8 ‘ 
197. In the Stem or branches, during the first year or season of their 
growth, the difference between Exogens and clepr is not alw aes very 
i 8 
conspicuous. oth there is a tendency t cular arrangem 
e sc stem, leaving the centre dae: ned or filled ey 
cellular tissue (pith) only, and a more or i imi need 1 3 
in several Endogens. More ently, however, the distinc- 
tion is already very apparent the first s oi, especially sowaide its close. 
The fibro-vascular bundles in Endogens usually anastomose but little, 
passing continuously into the branches and leaves. In E xogens the circle 
o-vascu orms a 
of fibr lar ois 8 ore pon gn cylinder of network 
emitting lateral offsets into the branches and 
The iaseainta stem, after the first year ‘of ae owth, — ez 
the pith, a ncaa of rein ge ey ng “the centre or long 
tudinal axis of a. ste It is y in young stems or as sen 
becomes ro Brproeet as Fike wood hakieee, and often finally 
disappears, or i ely distinguishable in old tree 
with the leaf-buds and branches, with the petioles a beget! 
nd v of 
other ramifications of the system. Like the pith, it ate prbhes he 
in old w ood. 
ing what is cal 
wood or duramen, the outer, younger, — sually paler- cccloatel living 
in wo lbw: 
_. 4. the medullary ra ys, which form Santen plates, originating in the 
ad a radiating from gpa traverse the wood and t 
hi 
face. e ee is formed, the inner port of the m 
ray e, but they usually cid still Ba seen in old serad | 
forming what vr Resap ia call the silver — 
e bark, which lies —— the the epidermis. 
arranged in 
within It 
— ee wood, nnual concentric circles 1), of which the 
d forming t 
‘ ar ayer or . r 
bart which. as it is distended by the thickening of Bik stem, either cracks 
8 cast off with epidermis, — is no longer distinguishable 
Within the ei leva is the cellular, or green, or middle bark, formed 
of loose thin-walled pulpy cells containing’ ge hy aa (192); and which 
is usually the layer of se preceding seas innermost and youngest 
oun a he is the shee or inner bark, formed of long 
199. The anlogesons stem, as it grows old, is not marked by the con- 
. The wood consists of a matrix of cellular tissue 
