OUTLINES OF BOTANY. LXES 
formation of a new layer or ring of bark within the innermost preceding 
ayer and outside the new ring of wood, thus forming a epiesge a 
concentric circles. The sap elaborated by the leaves finds its way, in 
manner n e the ca 
of tender thin-walled cells con the wood with the bark, by the 
divisio rgement of wh new cells (190) are formed. Thes 
lls separate in layers, the inner ones constituting the new ring of wood, 
an ut nes tl w bark e e trees, in 
temperate climates, bon seasons of growth correspond with the years, and 
the rings of wood remain Viteienty distinct to indicate the age of the 
ree; but in many tropica cal and some evergreen trees, two or more rings 
of — are formed in one year. 
In endogenous perennial yore Sear the new wood or woody fibre 
is Tahiled towards the end of the stem, or irregularly mingled with the 
old. The stem ab paid aoe only boonies ‘note dense without 
increasing in thickn or only increases by gradual distention, which 
is never very considerable, eM Y ror aistetore no certain criterion for 
judging of the age of the 
213. Flow Joue general, all their eae formed, or indicated by Ee pro 
tuberances F eect cells very early s stage 0 of the bud. Thes a pack 
e then usually mo re r iets placed than in ca dead developed flower. 
Parts which chapels cies are oo distinct, y are present in this 
rudimentary state which are never fu sive de vanced and parts which 
are afterwards ae es a or diss imilar are perfectly alike at this early 
period. On this account flowers in this very early stage are supposed 
by some modern tous sts to be more normal, that is, more in confor mity 
to a supposed type; and the study of the early formation and growth 
of the floral organs, called Organogenesis, has been sider ps Bago 
for the correct paige a of the affinities of slanie In cases, 
however, it would appear that modifications of development, or to be 
detected in the very young bud, are yet of great importance in the 
distinction of large groups of plants, and that “Onganogenesis, although 
often assist in clearing up a doubtful point o nity, cannot 
nevertheless be paris et ed relia on in estimating the soil value of pe- 
culiarities of structu 
214. The flower is considered as a bud (flower-bud, alabastrum) until the 
Sm expands, the period of flowering (anthesis) is that which elapses 
spon the first exp Rent ‘of the perianth, till the nistil is set or begins to 
enlarge, or, when it does not set, until the stamens and pistil nee or 
fall. After that, the enlarged ovary takes the name of young frui 
e b 8 
plants, many plants form also, at or near the bud or see eed, hie de eposits, 
chiefly of starch. In many cases—such as the tubers of a potato or other 
the scales or thickened base of a bal , the albumen or the 
nw 
ci 
supply it from without. In rever, such as the fleshy 
thickening of some stems or poeane * the em carps of fruit which perish 
tong before germination (the first growth of the seed), neither the use 
r the cause of these depoaike has as yet been clearly explained. 
