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smaller subdivisions. It is easier to find points of connection between this group 
and the Filicineae, such, for instance, as the similarity in the composition of the 
fibrovascular bundles, and certain modifications of the fundamental tissue which 
occur in the two classes, but the external conformation is the most important point 
to be considered as an indication of relationship. In the Filicineae the well-developed 
leaves form the principal morphological feature, whereas in the Dichotomese they are, 
though numerous, of very simple structure and of small size ; in the one class the 
external conformation depends upon the stem, in the other upon the leaves. It is of 
great importance to note that each leaf, in the Dichotomeae, produces a single 
sporangium, whereas each leaf, in the Equisetaceae and Filicineae, bears several 
sporangia. In this group the sporangium arises typically near to the base of the 
leaf, and it is of but little consequence that in some cases it arises further back 
from the axil of the leaf or even from the stem ; this is merely an example of an 
occurrence common among Phanerogams that organs of the same morphological 
value (in their case the branches) arise at one time at the base of the leaf, at another 
in its axil, or even from the stem above the axil. Although it has already been 
pointed out that the mode of development of the sporangia is insufficient to define 
the principal subdivisions of the Vascular Cryptogams, it must be remarked here that, 
in contrast to the various modes occurring in the Filicineae, the mode of develop- 
ment of the sporangia is constant, even when the other morphological characteristics 
are widely different ; here the sporangium is always developed from a group of cells. 
A short definition of the two orders — I. Lycopodiaceae, II. Ligulatae— is given at 
the close of the introduction to the Vascular Cryptogams. 
Order I. Lycopodiace^ ^ 
I. The Sexual generation (Oophore). The conditions which are necessary for 
the germination of the spores of Lycopodium^ Psiloium, etc., are as yet unknown. In 
spite of the very numerous attempts made to cultivate them only one observer. 
De Bary, has succeeded in obtaining the early stages of the development of the 
prothallium of Lycopodium inundatmji. The endospore protruded as a spheroidal 
vesicle from the exospore which had split into three valves : the vesicle was then 
divided by a transverse septum into an inner basal cell, which underwent no subse- 
quent alteration, and an outer cell which grew like an apical cell and formed two 
rows of segments. Each segment was then subdivided by a tangential wall into an 
^ Bischoff, Die cryptog, Gewächse. Nürnberg 1828. — Spring, Monographie de la famille des 
Lycopod. (Mem. de I'Acad. roy. Beige, 1842 et 1849). — Cramer, über Lycop. Selago in Nägeli und 
Cramer, Pfl. phys. Unters. Heft 3, 1855. — De Bary, über die Keimung der Lycop. in Ber. d. naturf. 
Ges. zu Freiburg-i-Br, and Ann. Sei. Nat. 1858. Heft IV. — Nägeli und Leitgeb, über die Wurzeln, 
in Nägeli's Beit, zur wiss. Bot. Heft 4, 1867. — Payer, Botanique cryptogamique. Paris 1868. — 
Hegelmaier, Bot. Zeit. 1872, — Russow, Vergl. Unters. Petersburg 1872. — Mettenius, über Phyllo- 
glossum. Bot. Zeit. 1867. — Juranyi, ühtr Psilotum. Bot. Zeitg, 1871. — Fankhauser, Bot. Zeitg. 1873. — 
Strasburg-er, Bot. Zeitg. 1873. [Arcangeli, Studii snl Lycopodium Selago, 18^4. — Prantl, Bemerk, üb. 
d. Verwandtschaftsverhältnisse der Gefässkryptogamen ; Verh. d, phys.-med. Ges. zu Würzburg, 
1875. — Braun, Blattstellung und Verzweigung bei Lycopodium, Sitzber. d. bot. Ver. d. Prov. Branden- 
burg, 1874. — Hegelmaier, Zur Kenntniss einiger Lycopodinen, Bot. Zeitg. 1874. — Bruchmann, Ueb. 
Anlage u. Wachsthum der Wurzeln von Lycopodium, Jenaische Zeitschrift, 1874.] 
