4 THE CELLS OF MOSSES. 



plant life. These will be found in varying quantity and of differ- 

 ent dimensions in various mosses. They are especially large in 

 the leaves of Funaria hygro?netrtca and some species of Barbiila ; 

 while in Bryum argenteum a large proportion of the leaf-cells has 

 no chlorophyll, which produces the shining, silvery appearance 

 from which has been derived its distinguishing name. And again, 

 others of the Bryw?i^ Hyp?iu77i^ and Sphagjimn have such a small 

 allowance of chlorophyll as to be partly transparent. 



When we come to examine the combinations or aggregations 

 of cells forming the tissues of which the mosses are composed, we 

 meet with simple examples of the various ways in which they are 

 united in various parts of mosses. Thus, what botanists call ce/l- 

 masses, where the cells are united in all directions of space, may 

 be found very distinct in the young or early stage of the sporan- 

 gium, or urn, or fruit-vessel; and cell-ro2us, in which simple cells 

 are in contact only at the opposite ends, exist in the early or pro- 

 tonema threads just referred to, and in the red radicles, which are 

 produced more or less near the base of all mosses, except some 

 SphagmuHs, and with which the stems of some so abound as to 

 felt them together ; for instance, Mnium hormim^ Campylopus 

 Jiexuosus, Breutelia arcuata, and Dici'anella heteronialla^ and in the 

 lamellae on the upper surface of the leaves of Polyti-ichum and 

 Torula ericmfoUa. Cell-surfaces^ where the component cells form a 

 single flat layer, united in two directions of space, are illustrated 

 by the leaves of most mosses, more particularly those of Mnium 

 pu?ictata^ Fontinalis aiitipyretica^ all the Spliagnu?n family, and 

 Hookeria lucens ; while fibro-vascular bundles of the simplest 

 kind, the beginning of cell-bundles and the commencement of 

 woody structure, can be discerned in portions of the stem of 

 Polytrichum and Bryum. 



Cell-groups^ or families of similar cells, are found in the gemmae 

 of Aulacomnion pahtstre and Aulacomnion androgyftum^ OrtJio- 

 trichiwi Lyellii^ Ulota phyllantha^ and Barbula papulosa. 



Most of the Mosses afford ready subjects for studying the walls 

 of tissue cells, nearly all without any preparation ; while those 

 which are dark and incrassated, like the Andreceas, can be 

 quickly brought into a requisite condition by the application of a 

 solution of caustic potash and water. The Sp/iagJiums, Pottias^ 



