FILTCINEJE. 461 



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 diff'erent; 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 inundatum. 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. Gewachse. Niirnberg 1828. — Spring, Monographic de la famille des 

 Lycopod. (Mem. de I'Acad. roy. Beige, 1842 et 1849). — Cramer, liber Lycop. Selago in Nageli und 

 Cramer, Pfl. phys. Unters. Heft 3, 1855. — ^^ Bary, iiber die Keimung der Lycop. in Ber. d. naturf. 

 Ges. zu Freiburg-i-Br. and Ann. Sci. Nat. 1858. Heft IV. — Nageli und Leitgeb, iiber die Wurzeln, 

 in Nageli's Beit, zur wiss. Bot. Heft 4, 1867, — Payer, Botanique cryptogamique. Paris 1868. — 

 Hegelmaier, Bot, Zeit. 1872. — Russow, Vergl. Unters. Petersburg 1872. — Mettenius, \xher Phyllo- 

 glosstim, Bot. Zeit. 1867.— Juranyi, \xh&x Psilohim. Bot. Zeitg. 1871. — Fankhauser, Bot. Zeitg. 1873. — 

 Strasburg-er, Bot. Zeitg. 1873. [Arcangeli, Studii sul Lycopodium Selago, 1874.— Prantl, Bemerk. lib. 

 d. Verwandtschaftsverhaltnisse der Gefasskryptogamen ; Verb. d. phys.-med. Ges. zu Wiirzburg, 

 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.] 



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