24 



KNOWLEDGE 



[February 1, 1892. 



antherids; hence it probably is that this form of leaf 

 prevails in Mosses living in dry situations, just as the thick 

 leaves of succulent plants are found iu similar situations. 



The. capsule.— Oi all the organs of a Moss plant, the 

 capsule which produces the spores is, perhaps, the most 

 peculiar and characteristic. If the reader will refer back to 

 Figs. 1 and 2, he will see the capsules (c in Fig. 1, r( in 

 Fig. 2) borne on the end of the long stalks (s). The cap- 

 sule, as is shown in Fig. 2, is covered with a delicate veil 

 or calyptra, which is shown as removed at cal. This veil 

 is the remains of the archegone, borne up by the stalk or 

 seta in its upward growth. In the case of the Polytrichum, 

 it is covered with a thick coating of depending hairs, a cir- 

 cumstance which gives its name to the genus. When the 

 veil is removed, the capsule itself is disclosed (c in Fig. 2), 

 surmonuted by an operculum or lid (o), which fits on to the 

 top of the capsule like the lid on a box. The capsule with 

 the lid removed is sho^^^a at the letter <•'. 



If the reader will refer back to table A, he will find that 

 the Acrocarpous Mosses, i.e., those which produce their 

 capsules at the end of the axis, are divided into Stegocarpaj 

 and CleistocarpsE. We are now in a position to appreciate 

 this distinction. In the Cleistocarpous Mosses, the 

 capsule is never differentiated into the two parts of the 

 true capsule and lid; it remains always as a closed 

 capsule until the walls decay or break, and so emits the 

 spores which it contains. Of this class, the clay Moss or 

 Phascum (Fig. 17) is a familiar example. As a whole, 

 this class is less highly organized than the Stegocarpous 

 Mosses— such as the Polytrichum — where the capsule, 

 originally a single organ, becomes differentiated into the 

 two parts already described, and the spores are retained in 

 the capsule dry and snug imtil the ripened lid falls off and 

 allows their escape. 



In some cases, the orifice of the capsule 

 is formed by a smooth edge or lip ; but 

 in other cases this orifice is surrounded 

 by a, girdle of teeth of varying nmnber, 

 form, and colour, so that the study of 

 the peristome, as this girdle is called, 

 presents a continued variation of objects 

 of beauty and interest. Fig. 22 exhibits 

 the peristome of the beautiful little Moss 

 the Tetraphis peUudda, to which I have 

 already referred. No simpler form of 

 peristome can be found than this, ex- 

 hibiting four teeth in a single ring. 

 23 is part of the peristome of the Fissidcns adiinitioides 

 magnified, and 



shows two pheno- 

 mena common in 

 peristomes, (1) the 

 division of the 

 teeth at their free 

 ends, and (2) the 

 presence of trans- 

 verse markings, 

 generally of a 

 darker colour than 

 the intervening 

 spaces. A tooth 

 thus marked is said 

 .^^S^TrJ'Tf^t^T^i^^ to be trabeculated, 

 ^^-.j' .',;:' , '■ ,-'/,l^^ i-e., marked by 

 ■ '" ''--'■■'" trabeculffi, or little 

 riG.23.— Part of peristome beams. Fio. 24. 



oiFissidensadian/ioides, In one consider- ^<''''^^omc of 

 u.agn.ned. AfterSehim- ^^le family of ^^H^M^:; 

 ^ Mosses, some of Srhimper. 



Fig. 22. 

 Peristome of 

 Tetraphispel- 

 lucida, after 



ScUimper. 



Fis 



Fig. 2.5. — Capsule and 

 peristome of Poly- 

 trichnm. p. peris- 

 tome, t. tympaTium, 

 after nature. — A.F. 



which are very common on the tops of our walls, the teeth 

 are hair-like in length and delicacy, and are twisted into a 

 curious scroll like a lambent flame of fire. Fig. 24 

 represents one of these twisted peristomes from which 

 the genus especially characterized by it has received from 

 some botanists the name of Tortula. 



Again, in another form, which exists in Polytrichum, 

 the teeth assume a very different appearance and connec- 

 tion. To make this intelligible I must refer to a portion 

 of the structure of the capsule to which I have not hitherto 

 referred, the columella, or little column, a central stem 

 which occupies the very axis of the 

 capsule ; this, in Polytrichum, 

 emerges from the mouth and ex- 

 pands into a tympanum or drum- 

 head, and the teeth arising from the 

 lip of the mouth join and support 

 this drumhead, leaving interspaces 

 between them something like long 

 narrow windows under the flat roof 

 of a circular tower, through which 

 the spores escape. Fig. 25 is a re- 

 presentation of this singular struc- 

 ture, in which //. marks the place of 

 the peristome or girdle of teeth : 

 these are seen to be attached to U, 

 the tympanum, into which the column has expanded. 



I have hitherto spoken of the peristome as consisting of 

 one girdle of teeth ; often it is double as in the great 

 genera Hypnum 

 and Bryum, and 

 then the teeth often 

 reach the number 

 of sixty-four. In 

 one foreign genus 

 (Dawsonia) there 

 are as many as four 

 circles of teeth. 



The accompany- 

 ing Fig. 26 is a dia- 

 gram intended to 

 assist the reader in 

 gaining a general 

 notion of the struc- 

 ture of the several 

 parts of a capsule 

 with a double peri- 

 stome : it is a dia- 

 gram only of a 

 section of an ideal 

 capsule, and not a 

 picture or repre- 

 sentation of any 

 existing capsule. 

 The reader who 

 will carefully in- 

 spect it will learn 

 what to look for 

 when he first holds 

 a capsule in his 

 hands, and may get 

 some assistance as 

 regards the techni- 

 cal language of 

 bryology. He will 

 see the calyptra, or 

 veil (eal.), the re- 

 mains of the ori- 

 ginal archegone ; he will see the operculum, or lid (oper), 



Fig. 26.- -Diagrammatic section of a capsule. 

 cfiL, calyptra ; oper., lid or operculum ; 

 ip., tooth of inner peristome ; op., tooth 

 of outer peristome ; an., annulus or ring; 

 col., columella ; sp., wall of the actual 

 spore sac ; ap., region of the aphvse. — 

 A. F. 



