333 
given off from the lowermost cell of the branches, sometimes also from the second 
and following cells. They are frequently formed in a number of three from the basal 
? 
Fig. 251. 
Callithamnion roseum. A—C, deve- 
lopment of the hairs. D, Fully 
developed hair pushed aside by a 
branch from the subterminal cell. 
A—C 700:1. D 300: 1. 
(fig. 254). The number of sporangia on a branch is often 
Cells bearing more than one sporangium 
only 1 or 2. 
cell; they grow in the outer membrane 
of the filaments but become partly free 
at the base of the principal axis, here 
forming free, pluricellular, branched fila- 
ments which fix the plant to the sub- 
stratum. The cortical layer may be so 
much developed that the cells of the 
filament are scarcely distinguishable. Ad- 
ventitious shoots do not occur or only 
: Fig. 252. 
exceptionally. Br #04 
1 AJ à Callithamnion ro- 
The tetrasporangia are usually  seum. Part of cell 
with chromatopho- 
res and Floridean 
starch, 
placed in a row on the upper (inner) side 
of the branches of the last order. The 
tetraspore-bearing branchlets are thus, 
as a rule, unbranched, but fertile branchlets more or 
less branched above not unfrequently occur. The tetra- 
sporangia-bearing branchlets are frequently alternate bi- 
seriate. The sporangia usually 
form a short row of 1—4 
or-5 on the lowermost cells, 
one on each cell (figs. 250 B, 
254, comp. Harvey, Phyc. 
Brit. Il. c. fig. 2—3), but the row 
is frequently interrupted, by 
single cells bearing no spo- 
rangium. Sometimes, the un- 
dermost articles are bare, and 
the formation of sporangia 
begins only at a higher level. 
The sporangia placed at some 
distance from the base are 
not always situated on the 
upper side but frequently on 
the flanks or even on the outer 
(under) side of the branch 
À Im 
| 
Fig. 253. 
Callithamnion roseum. Part of stem 
with corticating filaments. 50:1. 
have never been met with. The ripe sporangia are (60—) 
70—80 (—84) u long, 45—55 (—70) w broad. Once I found an unusually large spo- 
rangium measuring 98 x 74 u. The sporangia open by a transversal slit above. 
D. K. D. Vidensk. Selsk. Skr., 7. Række, naturvidensk. og mathem. Afd. VII. 3. 43 
