CKYPTOGAMOUS PLANTS. 635 



Sub-Kingdom II. — Ceyptogamous Plants. 



FlowerUss Plants, having sexual organs, and producing spores, hut han]ing 

 neither stamens, nor pistils, nor seeds. 



Class. III. — Aoottledones, Juss. Cellblaees and MoNO-CKTPrOGAMa:, DC. 

 Thallophyta and Aorobrya, Bndlich. Thalloqens and Aoeogens, Lindl. 



The plants belonging to this Class are in some instances composed 

 entirely of cellular tissue ; in other instances both cells and vessels 

 are present. The vascular tissue in the higher orders consists partly 

 of closed spiral and scalariform (fig. 64) vessels. Many of them have 

 no true stem nor leaves. The woody stem, when present, consists of 

 simultaneous vascular bundles, which increase in an acrogenous man- 

 ner (p. 70). The stem of Tree-ferns (which illustrates this class) is 

 unbranched, more or less uniformly cylindrical, hollow in the interior, 

 and marked by the scars of the leaves (fig. 135, p. 71). Stomata 

 occur in the epidermis of the higher divisions. Leaves, when present, 

 have frequently no true venation, at other times the venation is 

 forked. There are no flowers, and no distinct stamens nor pistils. 

 Eeproduction takes place by the union of cells of different values, 

 some representing the male element, and called Antheridia, others 

 the female, and called Archegonia (p. 265), by means of which 

 germinating bodies called spores are formed (fig. 594, p. 334). The 

 spore may be considered as a cellular embryo which has no cotyledons, 

 and germinates from any part.of its surface, being heterorhizal (p. 334, 

 fig. 629, p. 356). (For a full account of Cryptogamic reproduction 

 see pages 266-281.) 



Sub-class I. — AcEOGEN^, jEtheogam^ oe Coemogen>b. 



Acotyledons, having usually distinct stems and leaves (fronds), 

 etomata, a certain amount of vascular tissue, and sporangia or thecse 

 (spore-cases), containing spores. This sub-class corresponds in a great 

 measure with the division of Oormophyta, called Acrobrya by End- 

 licher, and with the Foliosse or jSltheogamse of De OandoUe, and 

 Angiosporse of other authors. The Antheridia contain ciliated 

 antherozoids or spermatozoids, and the spore in germination forms a pro- 

 thallus on which Archegonia are produced, which are fertilised by the 

 spermatozoids. Equisetums and Ferns have only one kind of spore, 

 a,nd are called Isosporous {'Idog, equal), while Marsileas and Lycopods 

 have two kinds of spores (microspores and macrospores), and are 

 called by some Heterosporous (eVsgos, diverse). The microspores have 

 & minute imperfect prothallus, with an antheridial ceU containing 



