DEFINITION AND CLASSIFICATION OF LEAVES. 593 



resist strains and bending pressures. Just as we distinguish soft, pulpy animals 

 from such as are provided with skeletons, so also we distinguish soft plants, without 

 wood and hard bast, from hard plants possessing these tissues. I would only point 

 out this analogy in passing, and avoid entering into any further discussion upon it 

 lest thereby misconceptions might arise. In discussing the hypotheses relating to 

 the history of development of the whole vegetable kingdom in the second volume, 

 I shall take the opportunity to return to these analogies, as well as to the relation 

 of the habitat to the structure and form of plants. There the speculations about 

 the evolution of plants on the ground of the comparison here only indicated will 

 receive an impartial consideration. In this place, however, such discussions would 

 be premature, and our remarks might share the same fate as the speculations of 

 the Nature-Philosophers of which examples were quoted on p. 13 of the Intro- 

 duction. 



2. FORM OF LEAF-STRUCTURES. 



Definition and classification of Leaves. — Cotyledons. — Scale-leaves, Foliage-leaves, Floral -leaves. 



DEFINITION AND CLASSIFICATION OF LEAVES. 



— 'T is written — " In the Beginning was the Word." — 



Already at a stand — and how proceed ! 



Who helps me? Is the Word to have such value, 



Impossible — if by the spirit guided. 



Once more— "In the Beginning was the Thought." — 



Consider the line first attentively, 



Lest hurrying on the pen outrun the meaning. 



Is it Thought that works in all, and that makes all? 



— It should stand rather thus: — "In the Beginning 



Was the Power." — yet even as I am writing this 



A something warns me we cannot rest there. 



Of this speech — which Goethe puts into the mouth of Faust — the naturalist is 

 involuntarily reminded when he attempts to explain terms which popular language 

 from time immemorial has associated with certain ideas. These terms have later 

 gained admission into scientific terminology, and here, once adopted, have gradually 

 been employed to indicate things which no longer correspond to the original 

 current notions. Whosoever introduced into common language the words "leaf", 

 " stem ", and " root ", little suspected how difficult it would come to be, to say, 

 shortly and exclusively, what botanists mean by these designations — to write down 

 what the man of science understands by a leaf, a stem, a root; nor did he surmise 

 that over the question as to whether or not certain plant-structures should be 

 regarded as leaves, and should be so named, continuous eager strife would rage 

 1 amongst the learned, and that the polemic writings on this matter, if carefully 

 I collected, would fill a book much more extensive than the present one, in which I 

 am attempting to describe the life of the whole Vegetable World. 



