438 



BOTANY 



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

 the sporogonia developed from them. 



(a) Bryinae acrocarpae'. The archegonia, and consequently the sporogonia, are 

 terminal on the main axis. Mnium undulatum (Fig. 395) and hornum, Poly- 

 trichum commune (Fig. 392), and Funaria hygrometrica are common examples. 

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

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

 other shoots that are sterile, with two rows of leaves (Fig. 393 A, B). The 

 protonema of this species is peculiarly constructed and gives out an emerald 

 phosphorescent light. (Of. Figs. 172, 214.) 



(b) Bryinae pleurocarpae. The growth of the main axis is unlimited, and the 



Fio. 308. Mnium hornum. A, Capsule with upper portion of seta ; ap, apophysis ; p, peristome ; 

 d, the separated operculnm. B, Three teeth of the outer peristome seen from the outside ; an, 

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

 (A x 4 ; B, C x 60.) 



archegonia with their sporogonia arise on short, lateral branches (Fig. 394). In 

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

 Mosses belonging to the genera Hylocomium, Neckera, and Hypnum, which are 

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

 Moss, Fontinalis antipyretica. 



, 



III. PTERIDOPHYTA (VASCULAR CRYPTOGAMS) ( 



The Pteridophytes include the Ferns, Water-Ferns, Horse-tails, and 

 Club Mosses, and represent the most highly developed Cryptogams. 

 In the development of the plants forming this group, as in the Bryo- 

 phyta, a distinct alternation of generations is exhibited. The first 

 generation, the sexual, bears the antheridia and. archegonia; the 

 second, the asexual, develops from the fertilised egg and produces 

 asexual, unicellular spores. On germination the spores in turn give 

 rise to a sexual generation. 



