442 



BOTANY 



I'AllT II 



386), the teeth from portions of the external wall, and the cilia from portions of 

 the internal walls of the same layer. On the opening of the capsule the un- 

 tlnckened portions of this layer break away and the teeth and cilia split apart. 

 Tlie transversely ribbed markings on their surface indicate the position of the 

 former transverse walls. 



The structure of the iieristome varies greatly within the Bryinae. By its 

 peculiar form and hygroscopic movements the peristome causes a gradual dis- 

 semination of the spores from the capsule. 



Variations in the form of the capsule, peristome, operculum, and calj-ptra afford 

 the most important means of distinguishing the different genera. The Bryinae 

 are divided into two sub-orders, according to the position of the archegonia or of 

 the sporogonia developed from them. 



(«) Bryinae acrocarpac. — The archegonia, and consequently the sporogonia, are 

 terminal on the main axis. Mnitim undulatum (Fig. 383) and hornum, Poly- 









Fig. 387. — -Uftiuw hornum. A, Capsule with upper portion of seta; up, apophysis; p, peristome; 

 rf, the separated operculum. B, Three teeth of the outer peristome seen from the outside ; an, 

 annulus. C, inner peristome seen from the inside; u; broader cilia; h, narrower cilia. 

 (.-1x4; B, Cxf)0.) 



trichum commune (Fig. 381), and Fionaria hygrometrica are common examples. 

 Schistostega osmundacea, a moss living in caves, has fertile shoots, wliicli have 

 spirally arranged leaves and bear stalked capsules devoid of peristomes, and also 

 other shoots that are sterile, with two rows of leaves (Fig. 382, A, B). The 

 protouema of tliis species is peculiarly constructed and gives out an emerald 

 phosphore.scent light. (Cf. Figs. 205, 206.) 



{b) Bryinae 2)leurocar'pae. — The growth of the main axis is unlimited, and the 

 archegonia with their sporogonia arise on short, lateral branches (Fig. 384). In 

 this group are included numerous, usually profusely-branched species of large 

 Jlcsses belonging to the genera Hylucomium, Neekcra, and Hypnum, whicli are 

 among the most conspicuous mosses of our woods, and also the submerged Water 

 Moss, Fontinalis antipyretica. 



III. PTERIDOPHYTA (VASCULAR CRYPTOGAMS) (!'«- ^--) 

 The Pteridophytcs include the Ferns, Water-Ferns, Horse-tnil.s, and 



