194 ON TUE STUDY OF THE MOSSES. 



The spores are minute, round, cellular bodies, varying in size, colour, 

 and external marking, and are composed of t\vo membranes or coats, an 

 inner and an outer one, enclosing a thickened granular mass. Though 

 similar in function to the seeds of flowering plants, they diilcr from 

 those organs, in being capable of germinating from any part of their 

 surface, and in possessing no embryo, (the youii/j plant coiitaiiwd in the 

 seed;) hence plants developed from spores are termed Acotyledons, (Gr. 

 o, ■without, and kotuhdon, a seed-lobe.) The spores which are formed in 

 the capsule are the bodies from which the moss-plant is normally 

 develoi^ed. 



But many even of our common Mosses rarely produce their fruit, 

 and are perpetuated in other ways, as, for instance, by gemmae, which 

 may be seen forming little globular heads ('2c) on the top of a pale, naked 

 stalk (26) in Aulacomnion androgynum, (2,) so frequent on wayside banks,* 

 or from thread-like cellular bodies, abundant on the leaves of some 

 Mosses, Orthotrichum Lyellii, for instance, frequent on poplars, elms, &c., 

 or from bud-like bodies formed in the axils of the leaves, as in Bryiim 

 (Duiotinwn, found on sandy banks, or even detached leaves may give 

 origin to a new plant, as in Canqyyloinis pyriformis, frequent on heath 

 lands. 



When the spores germinate, they give rise to a green thread-like 

 body, called the protonema, (3a,) which is formed by the protrusion of 

 the inner membrane of the spore through the outer one. This, by 

 frequent cell-division, becomes elongated and branched. The primary 

 branch, at first green, frequently turns brown, and, in some cases, 

 penetrates the ground and performs the function of a root. The 

 secondary branches are well charged with chlorophyll, (green, granular 

 vintter in the interior of the cell,) and branch frequently. On various 

 parts of the protonema bud-like bodies arise, {3b.) These are the 

 rudimentary moss-plant. From the buds roots are sent down into the 

 medium, on which they grow. By frequently I'ex^eated cell-division 

 these buds develope into the leafy moss-stem. Mosses, like Ferns, 

 Horsetails, &c., grow at the apex only, and are hence termed Acrogens, 

 (plants which increase at the summit only.) 



The protonema, which looks very like masses of green conferva, 

 may be seen forming a velvety mass on the gi-ound in the neighbour- 

 hood of Mosses ; and if a portion of such masses is examined with 

 the microscope, all the stages of growth may frequently be seen. In 

 most Mosses the pi-otonema is short lived, perishing befoi-e the moss- 

 plant is fully grown ; but in some of the lower forms, as in Phascum 

 terratum, it lasts throughout the plant's lifetime. This Moss may be 

 found in fallow fields, in Autumn and Spring. The gemmaa, above- 

 mentioned, germinate much in the same way as spores, forming first 

 the thread-like protonema, upon which the leafy stem is developed. 



The stem varies in length considerably ; in some Mosses it is imper- 

 ceptible without a lens, as in Phascum serratum, but in many others it is 

 very apparent. It may be erect, as in Polytrichum; or prosti'ate, as in 

 some of the Hypnium, or feather-mosses ; simple, as in Potlia, (4) ; or 

 * (2d) is one of tlie geruuia; detiiclied auii maguilied. 



