Geology and Natural History. 61 
its summit (Cunninghamia, &e.); the ovules thus correspond 
each to the lobe of a leaf. In other cases the ovules terminate 
the leaf; then each half of the blade may be transformed into an 
ovule (Ginkgo, Cephalotaxus), or the whol blade may be trans- 
formed into a single ovule (Zawus, Phyllocladus Podocarpus) ; 
sometimes the petiole is much lengthened (Ginkgo), but oftener it 
is very short, and the carpellary leaf is then wholly transformed 
into two ovules ( Cephalotaxus), or into a single one (Podocarpus). 
as sta ‘ 
? . 
have a free or superior, others an inferior or adherent ovary. | 
It follows that Coniferw form one indivisible natural family,— 
8 
Sucli are the principal features of a view which throws new light 
upon the morphology of the Gymnospermous plants, vindicates 
9. Van Tieghem, Anatomy of the flowers and fruit of Mistletoe 
(Viseum album).—Upon this subject the distinguished Dutch 
Vegetable Anatomist has published in Ann. Sci. Nat., ser. 5, t. 12, 
an elaborate and interesting, albeit considerably theoretical, paper, 
ote up the line of research, and the ideas which he had pur- 
ora 
fecundation: that in Viscum this ovule is reduced to the greatest 
possible simplicity, viz: to its essential part, the embryo-sac. His 
main conclusions are,— : 
_ (1.) That the male flower consists of four simple leaves only, that 
18, of two decussate pairs, each polliniferous upon the superior or 
inner face, and not of 8, as before supposed, 1. e., 4 sepals and 4 
stamens superposed to and connate with them. 
