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II Litophloea, the latter with several subgroups. This division 
he based upon the fact that in I the cortical cells of stem and branches 
are fibrillose, i.e. have their walls inwardly beset by spirally ascend- 
ing thickenings of the membrane, while in II this is never the case. 
As a matter of fact this is but one of several characters which sepa- 
rate these two very distinct types of Sphagnum. 
The cortical branch-cells of I are relatively large and entirely ho- 
mogeneous, the outer wall commonly containing a large round pore at 
upper end, sometimes also a second one below, while in II these cells 
are usually differentiated into two sorts, only the longer ones having 
a pore, and this terminating a longer or shorter neck- like extension of 
the cell-wall, the larger cells being then roughly flask- or retort- 
shaped ; in the few species which show uniform cortical branch- 
cells, either the ceils are all somewhat retort-shaped, or the retort- 
cells are almost or entirely suppressed. 
A fundamental difference of leaf-structure finds its most conspicu- 
ous expression in the fact that the branch-leaves of In^phloea are 
cucullate, while those of Litophloea are never so, but toothed across 
a broader or narrower curved or truncate apex, a relation explaining 
in the former case the origin of the specific name, 5. cymbifolium, and 
so of the current group- name, Cymbifolia for Inophloea. In Inophloea 
the outer surface of the branch-leaf is roughened in the vicinity of its 
apex, as shown in Braithwaite’s figures, a condition produced by the 
strongly projecting membrane of the hyaline cells, their outer mem- 
brane in this region being resorbed in a large gap in the end of the 
cell nearest the apex of the leaf, leaving the remaining membrane of 
the lower part of the cell projecting with marked convexity ; this con- 
dition of things is entirely foreign to Litophloea. The leaves of 
Litophloea show furthermore border- differentiation not found in 
Inophloea, the margin, aside from the toothed apex, being bordered 
by two or more rows of narrower, thinner, cells ; in Inophloea 
the network of alternating chlorophyll and hyaline cells simply 
ends with a chlorophyll-cell on whose outer side the so-called 
resorption-furrow represents the beginning of what would have been 
the next hyaline cell. If one look at the leaf-edge as the leaf lies flat 
on the slide, this remnant of the next hyaline cell appears as a very 
slender, nearly hyaline strip outside the last irregular line of chloro- 
phyll-cells, somewhat broadened at cell-ends, where rudimentary 
traces of outwardly forking chlorophyll-cells give the margin a den- 
ticulate effect. 
The stem-leaves as a further aspect of the same structural princi- 
ple show in Inophloea the hyaline cells merely uniformly narrowed 
throughout the basal part of leaf, while Litophloea has invariably a 
side-border of several rows of narrow cells, and usually in ad- 
dition a strong tendency to a suppression of the hyaline cells in 
the whole basal side regions (though the middle base always shows 
