5GG 
MR, F. 0. BOWER OX THE COMPARATIVE MORPHOLOGY OF THE 
should be applied to the leaf as is usual in studying the stein. On reading 
current morphological papers, however, it is very apparent that this is not done. 
Leaving out of account the use of that adhesive terminology, which constantly revives 
in the mind the older mode of viewing the leaf, it is still obvious that the treatment 
of the leaf by modern writers is different from that of the stem. Thus, to take as an 
example the best of the earlier works on leaf-development, viz., Eichler’s Dissertation 
on tfie Development of the Leaf ;* after defining the Primordial Leaf as the young 
leaf before internal differentiation, or distinction of external parts, the author goes on 
to describe (p. 7) how the primordial leaf becomes differentiated into “ two chief parts, 
which are common to the leaves of all Phanerogams, viz., a stationary zone, which 
takes no part in the further formation of the leaf, and a vegetative part which 
forms the lamina with its branches.” The former he names the foliar base (blatt- 
grund), and the products of its development are the sheath and the stipules if 
present; the latter he designates the upper leaf (oberblatt), which gives rise to the 
simple or branched lamina. The petiole is also, according to Eichler (p. 8), derived 
from the upper leaf, though other more recent writers describe it as being intercalated 
between the two parts. This distinction first drawn by Eichler has recently been 
revived, and the terminology, with some slight modifications, adopted by Goebel, f 
He has however imposed a very necessary limitation upon its application, viz.: that the 
two parts of the primordial leaf “ are not sharply marked off from one another, but are 
only to be distinguished by the part which they play in the further growth of the 
young leaf.” He has, on the other hand, extended it to the Monocotyledons and Gym- 
nosperms, and occasionally also to certain Cryptogams, in which similar phenomena 
appear. Thus the distinction of the foliar base and upper leaf has become established 
in botanical terminology, and it is applied equally to both branched and unbranched 
leaves. 
This distinction is a very natural outcome of the study of the development of 
the leaves of the higher plants, and it seems to lie ready to hand, but the comparison 
in this respect with the vascular plants, acknowdedged to be lower in the scale, has 
been much neglected, and such a comparison should be made as a test of the validity 
of a distinction of this kind. Because it appears to be obvious in certain of the 
higher plants, the distinction is not necessarily valuable, nor even logical; while, 
as I shall point out later, it is not in conformity with the morphological method of 
treatment of the stem. The parts resulting from the development of the foliar 
base and upper leaf are, it is true, ready distinguishable from one another in certain 
of the higher plants, but the question is whether we draw this distinction between 
structures which are morphologically coordinate, and whether by distinguishing them 
we gain any further insight into the real nature of the leaf. It appears to me that 
* Eichler, Zur Entwickelungsgeschichte des Blattes. Marburg, 1861. 
f Beitr. z. Morph, und Phys. des Blattes, Bot. Zeit., 1880, p. 753. Yergl. Entrr. d. Pflanzenorgaue, 
Schenk’s Handbuch, p 215. 
