Boyal Microscopical Society, 3 



emerge soaked with the water concealed therein. They can also 

 absorb atmospheric moisture and transmit it downward, thus taking 

 up again at night what they had lost during the day ; and by this 

 perpetual interchange the stagnant pools in which they flourish 

 never become putrid. The bark of the branches consists only of a 

 single layer of cells in communication with the innermost layer of 

 the stem bark ; but these are of two forms, for besides the ordinary 

 kind, there are others of a flask shape, larger, and with a circular 

 orifice, one of which always falls at a leaf-insertion. 



The leaves of bog mosses are very pecuhar, and are well known 

 as an elegant microscopic object ; those of the stem are more remote 

 from each other than in mosses, and in all the species two complete 

 spirals contain five leaves (phyllotaxy f) ; their form is ovate or 

 tongue-shaped, with the base frequently more or less auricled. 

 Those of the branches are much narrower, and not only vary on 

 the two forms of branch, but on difierent parts of each. If we 

 look at a Sphagnum leaf in fluid with a sufficient power, the first 

 thing that strikes us is the beautiful sigmoid form of the areolation, 

 or cellular network; and next, the presence of a delicate fibril 

 forming spirals or rings on the inner wall of each cell, and by which 

 the thin membrane is kept expanded, while perforating the mem- 

 brane are distinct apertures or pores through which it is common 

 enough to find infusoria have passed, which may be seen sporting 

 about in the cell cavity ; and thhdly, that these large prosenchyma- 

 tous cells are always void of chlorophyl, and hence want the lively 

 green colour so noticeable in true mosses. 



This, however, is not all. A more careful examination will 

 show that between the walls of these hyaline cells are placed 

 extremely narrow parenchymatous cells, which do contain chloro- 

 phyl. Moldenhawer first detected these in 1812 ; yet Carl Miiller, 

 in his ' Synopsis Muscorum,' terms them intercellular ducts ; in no 

 case is there any approach to the formation of a nerve or midrib. 

 According to the colour of the chlorophyl in these parenchym cells, 

 is the colour of the Sphagnum tuft, only seen, indeed, in the hving 

 or moist state, but presenting endless shades of rosy red, purple, 

 vinous red, bluish green, ohvaceous, apple-green, and straw colour. 

 When dry or dead, the hyaline cells lose their transparency, and all 

 the species become more or less a dirty white. The spiral threads 

 are nothing but thickenings on the inner waU of the cell membrane, 

 such as occur frequently in the tissues of phaenogamous plants; in 

 one species only are they altogether absent, viz. the American 

 S. macropliyllum, which Professor Lindberg separates as the genus 

 Isocladus. 



The male flowers of Sphagnums differ also from those of mosses, 

 and -in their arrangement, and the form of their autheridia, resemble 

 those of HepaticaB ; they are grouped in catkins at the tips of lateral 



b2 



