EUROPE AND NORTH AMERICA. 19 
cymbtfolium will soon convince any one that it is a character on 
which no reliance can be placed. As the purpose of the fibres 
seems to be to preserve the shape of the vesicular cells and support 
their delicate walls, we should naturally expect to see them most 
abundant im the compact or denser forms, and such we find to be 
the case, for in the short, close-branched forms of S. acutzfolium the 
cells of the stem leaves are fibrillose throughout, but in the tall, 
slender forms they are altogether absent. 
The pores or foramina stand near the adjacent cell walls, and are 
usually found on the posterior surface, but in S. ¢ene//um they are on 
the anterior, and in a few species both front and back are perforated, 
asin S. vigidum. Their size varies in different species; thus in 
S. acutifolium and cymbtfolium they are very large, in S. sudsecundum 
and cuspidatum very small. Besides these, Russow calls attention 
to larger apertures which become visible after treatment with iodine 
and sulphuric acid, and indicate more extensive resorption of the 
cell membrane; thus in the lower part of a branch leaf of 
S. jimbriatum so treated, these large openings reach across the 
whole width of the cell. The word /umen is applied by continental 
authors to denote the clear space in the interior of a cell through 
which light is transmitted, or the space bounded by the internal 
lining of the cells. 
In S. fimbriatum, strictum, Lindbergit, and others which have 
stem leaves fringed at the apex, this appearance is due to resorp- 
tion of the membrane of the marginal hyaline cells, and con- 
sequent projection of the intermediate parenchym cells. 
The bracts or leaves of the perichetium which surround the 
elongated receptacle of the fruit, are much larger than the other 
leaves of the plant, and in areolation are intermediate between 
those of the stem and branches, though coming nearest to the 
former ; their chlorophyllose cells usually present deficiencies in the 
thickening layers of their walls, and these standing opposite each 
other resemble imperforate pits, not unlike the dotted pleurenchyma 
of the wood of conifers, and a similar condition is observable in the 
walls of young axile cells of the Sphagnum stem (Hofmeister’s 
‘Higher Cryptogamia,’ pl. xvii. fig. 9 4). 
The bracts of the male inflorescence correspond with the branch 
leaves in structure, though they are usually broader and shorter ; 
but they frequently are adorned in addition with rich colours, which 
vary according to the species. 
