30 NEW PUBLICATIONS. 
tlie woody plants of the Austrian empire. " Tt is well known, says 
the learned author, "that there are plants the leaves of which are so 
characteristic as to be determinable at first sight with ease and preci- 
sion. Ferns, Palms, Conifers, Oats, Hoses, and similar well-marked t\^eg, 
cannot be mistaken in their leaves. But whether perfectly isomorphons 
leaves exist in closely allied species, or in different Natural Orders, 
can only be determined approximately by a careful comparison of nu- 
merous forms. An examination of the woody plants of Austria shows 
that, although many large genera exist and similar leaf -forms appear in 
rery different Natural Orders, isomorphism of the leaves is observed only 
in such species the soundness of which is highly problematical. Even 
in large genera, — for instance, Saline, Rosa, P^^unuSy Genista, Ace?% etc., 
it is possible to draw up good diagnoses of the different species 
from the leaf only, if all characters are carefully noted. Similar 
leaf-forms belonging to different Natural Orders, — for instance, Co?ti' 
ferdB and Ericacece, Salicinea and Amygdalece, — can also be distinguished. 
It may therefore be regarded as settled that the members of any given 
flora may be known by their leaves only, provided the species are 
tolerably sound, — a result important, not only as regards fossil, but 
also as reo-ards existin«: vesretation. ' But this must be evident to anv 
J^«*V.« V..^*«V*>..j-j ,Vj^ 
one looking over the illustrations accompanying this work, or, still 
better, by consulting a herbarium. Practical gardeners and pomologists 
are able to distinguish by the leaf only, not only closely allied species, 
but also their numerous varieties and even forms. Indeed, it is not 
the isomorphism, but the polymorphism, of leaves which offers the 
greatest difficulties in determining a species/' 
Many of the difficulties of characterizing leaves are removed by 
nature-printing, which enables us to reproduce the shape and skeleton of 
a leaf far exceeding in correctness any description of figure that can 
be given. Constantin von Ettingshausen, by his valuable publications 
on the venation of fossil and recent plants, was the first who availed 
himself of this new process to demonstrate the importance of venation 
for systematic purposes; and the terminology which Ettingshausen was 
compelled to invent, has been adopted, with a few modifications, in the 
present volume. The arrangement followed in enumerating the species 
is that of Bartling-Endlichen But at the end there is made an " at- 
tempt" — the term is the author's own — to arrange them according 
to their leaves only. Leaves {folia') are divided into 
