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NG BaGK is pructupad hd Ph ysiological Botany. 
Stem beoanics itself inordinately developed, the buds whee 
are normally produced on it in large numbers either remain 
_ taltogether dormant, or give rise to weak immature organs 
or a few fasciated or, less often, separate branches. The 
terminal bud almost invariably ultimately Gisappears. Fascia- 
tion is frequently associated with curvatures, causing the 
production of peculiar forms resembling sickles or crosiers, 
ae _ as 1s not uncommon in the willow and ash. 
Far more numerous are the changes in form whidl 
affect the leaves. ‘These may be classified into Metamor- 
phosis of Leaves, Peloric Formations, and true Changes of 
ob OFYN, 
oe Goethe was the first to propound the theory, though 
somewhat poetically, that all the organs of the higher plants 
can be referred back to a single, or at least, to a very small 
number of fundamental forms ; that, in fact, every organ is 
either axial (stem), or foliar (leaf), or is compounded of 
these two. ‘That this is actually the case is shown, not only. 
- by the history of development, but also by a close investiga- 
tion of those abnormal processes which are called metamor- — 
1 phosts. According to Goethe a foliar organ must be con- 
"sidered the more highly developed the higher it stands on 
the axis of the plant, the nearer therefore it is to the centre 
| of the flower; and an ascending series can be constructed 
‘ as follows :—Leaf-spine |Leaf-scale], Foliage-leaf, Bract, 
 Sepal, Petal, Stamen, Carpel. The metamorphosis may be 
either progressive or retrogressive, according as the trans- 
Al _ formation of the foliar organs takes place in the direction of 
a higher or lower member of the series. Instances of re- 
ae trogressive metamorphosis are furnished by the production of 
_ Jeaf-spines and leaf-tendrils already mentioned, which may 
| be considered as consisting essentially in an abortion of the 
.  Jamina and a reduction of the leaf to the henified petiole 
zs or mid-rib. Equally common is the retrogression of bracts — 
to the form of foliage-leaves ; as in the spathe of Aroidee, | ed 
which often has a leaf-like form. The retrogtessiiam uae 
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