
GOETHE ON THE METAMORPHOSIS OF PLANTS. 5 
cotyledons and of the future leaves, varies in different plants; but they 
differ most from the cotyledons in being flat, and of a delicate texture ; 
and especially in being formed like true leaves, in being perfectly 
green, and in being situated on a visible node. Their connection with 
the future stem-leaves can no longer be denied ; they are neverthe- 
less inferior to them in the imperfect state of their margin. 
20. At each successive node the form of the leaf attains greater per- 
fection; the midrib lengthens, and the side-ribs which arise from it 
extend more or less towards the margin. The different relations of the 
ribs to each other are the priacipal cause of the various shapes we ob- 
serve in leaves ;* which are notched, deeply incised, or are formed of 
many leaflets, and thus resemble little branches. The Date Palm affords 
a striking instance of the most simple form of leaf becoming gradually 
but deeply divided. As the leaves succeed each other the midrib 
lengthens; till at last it tears asunder the numerous compartments of the 
simple leaf, and an extremely compound, branch-like leaf is formed. 
21. The development of the leaf-stalk keeps pace with that of the 
leaf; the stalk being either closely coherent with the leaf, or so formed 
as ultimately to be easily severed from it. 
22. We see in different kinds of plants that this independent leaf- 
stalk has a tendency to assume the form of a leaf ; as in the Orange. 
Its structure, which for the present we pass over, will afford us matter 
for future consideration. 
23. Neither can we now enter upon a closer examination of the 
stipules; we can only remark in passing that, especially in those in- 
stances where they constitute a part of the leaf-stalk,$ they share its 
future transformations in a remarkable manner. 
24, Whilst the leaves principally derive their first nourishment from 
* Schleiden, Trécul, and most modern observers hold that the mode of distribu- 
tion of the ribs of the leaf depends essentially on the form of the latter. De Can- 
dolle, however, was of the opposite opinion. 
T Trécul describes the leaf of the Date Palm as a compound leaf, the pinnules of 
which are attached by their points to a cellulo-fibrous cord, which surrounds the 
whole leaf. By the rupture of this cord, and by the peeling off, in thin scales, of a 
brownish pellicle, which at first covers the whole surface of the leaf, the piunules 
become at length separated from each other.  (Précul, Mém. sur la Formation des 
Feuilles, Aun. des Se, Nat. 3rd ser. vol..xx, p. 285.) 
i As illustrations may be cited the phyllodia, or dilated foliaceous petioles of some 
species of Acacia, Oxalis, etc. 1 À 
§ For a concise account of the different kinds of stipules, see Griffith, Notulæ, 
vol, i. p. 233. 
4 A aiea 
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