Allgemeines. — Anatomie. 
451 
A brief allusion is made in chapter XLVII to Heterospory and the 
Seed-Habit, and the whole argument of the Book is drawn together 
in the final chapter. It is there concluded that comparison of the 
several phyla of the Archegoniatae , as represented both by their 
fossil and their modern representatives, leads towards the recognition 
ol a primitive type, and that its construction in the several phyla 
of leafy forms has certain features in common. The chief of these 
are the definition of axial polarity in the first Initiation of the em- 
bryo: the continued apical growth: the radial construction of the 
shoot: the origin of the appendages laterally from the axis by enation, 
and in strictly acropetal order: protostelic structure of the conducting 
System of the axis, and a leaf-trace composed of a single Strand, 
which comes off from the protostele with the minimum of distur- 
bance of its structure. The appendages were from the first of two 
kinds which were closely associated together: bracts or leaves, and 
spore-producing members: the structure of these, and their relations 
to one another and to the axis varied in the different phyla, and 
gave to these their distinctive characters: but a whorled arrange- 
ment of the bracts was prevalent in early small leaved forms, while 
they commonly held a subtending relation to the spore-producing 
members. A body such as that sketched appears to have been com¬ 
mon for all the early Pteridophytes, and constituted the primitive 
shoot. There is no clear indication beyond comparison based on the 
facts of embryology and of mature structure how such a body was 
in the first instance produced: but this points to the strobiloid theory 
as enunciated in chapter XI. The Sporophyte thus constituted pro- 
bably arose originally as a structure of limited size and unbranched, 
upon a prothallus of considerable dimensions. From it, by branching 
of the axis, by differentiation of vegetative and propagative regions, 
by amplification of the leaves and spore-producing members, by 
adoption of an alternate leaf-arrangement as the leaves themselves 
enlarged, and by expansion of the vascular System to meet these 
additional requirements, all the known homosporous types may be 
understood to have originated. Author’s abstract. 
Drabble, E., Anatomy of the leaves of Agave rigida , Mill. 
(Quart. Journ. Inst. Comm. Research in the Tropics, Liverpool 
Univ. Vol. II, N°. 5, p. 141 —143, with plate. 1907.) 
The anatomy of the leaf of a variety of this species (C. elongata , 
Jacobi) is described in detail. Deep-sunk Stomata overtopped by 
four cuticular ridges occur on both sides of the leaf. The vascular 
bundles are scattered throughout the mesophyll. Those near the 
lower surface are normally orientated, those near the under, inverse. 
The fibres used in commerce are associated with the Xylem and the 
Phloem of the vascular bundles. D. T. Gwynne—Vaughan. 
Drabble, E., Sanseviera guinensis Willd, (Quart. Journ. Inst. Comm. 
Research in the Tropics, Liverpool Univ. Vol. II. N°. 5. p. 137—140, 
with plate. 1907.) 
The paper gives a detailed description of the anatomy of the 
leaf. Deep-sunk stomata overhung by cuticular projections from the 
epidermis cells at the ends of the Stoma. Many of the vascular 
bundles in the mesophyl are obliquely or inversely orientated. The 
