455 
The structure and development of the frond have been treated at length by 
FALKENBERG and Kyrın. Some supplementary remarks may be given here. 
Fig. 416. 
Rhodomela 
subfusca. Fæno 
Sund February. 
Trichoblast. 
150 : 1. 
The fronds issue from a parenchymatous dise from which new 
shoots arise as adventitious buds without any order (fig. 415). Ac- 
cording to FALKENBERG the lateral organs produced by the branching 
of the fronds are only branches except at the tips of the shoots which 
are closing their growth, where numerous hair-leaves are produced, 
on long stretches one on each joint, and above this region of hair- 
leaves a formation of branches never takes place. The latter assertion, 
however, does not always hold good, for in the upper part of 
the branched shoots basal cells of shed trichoblasts are frequently 
found and single branches frequently occur between the trichoblasts 
still in function. The branches of the last order bear only tricho- 
blasts. The trichoblasts and the branches are placed in a spiral with 
a divergence varying between !/, and ?/, (often nearly ?/;). When 
occurring between the trichoblasts the branches take the place of the 
latter in the spiral without a change of the angle of divergence. The 
spiral may be turning 
to the right or to the 
left, but there is no 
regular antidromy as 
stated by me in 1884 
(p.33 (5)). It seems that 
the spiral turns more 
frequently to the left 
than to the right, but 
my observations are not 
sufficient to ascertain 
that with certainty. 
The trichoblasts have 
the same structure as 
in Polysiphonia and other Rhodome- 
lacex. The first branchlet of the tricho- 
blast, however, is often given off from 
the third joint instead of from the 
second (fig. 416), or, though rarely, 
from the 4th, and unbranched tricho- 
blasts may occur, e. g. in f. fenuior. 
The second joint is often shorter than 
the following ones whether it bear a 
Fig. 417. 
Rhodomela subfusca. Upper end of male plant. 124: 1. 
branchlet or not. The cells contain a single nucleus and numerous chromatophores 
which are distinctly red. FALKENBERG lays much stress upon this fact which he alleges 
58* 
