number of specimens, how- 
ever, has led me to the 
conclusion that they are 
only marked types of a very 
variable species produced 
by the influence of the outer 
conditions. The first occurs 
in particular near the low- 
water mark, where it is ex- 
posed to the movement of 
the waves, whereas Rh. vir- 
gata grows in greater depth, 
in particular in streaming 
water but not exposed to 
the waves. In localities 
which are intermediary as 
to the outer conditions 
specimens intermediary as 
to the distinctive characters 
are also met with. In the 
outer characters it appears 
that e. g. individuals which 
453 
== 000 ST 
eu LUZ 
sin? 
Fig. 412. 
Rhodomela subfusca. Transverse sections of stems. A, & genuina. B, y virgata. 
160 : 1. 
if anything agree with Rh. virgata keep some branchlets which are not shed at the 
end of the period of vegetation, and do not show the above mentioned distinction 
: Fig. 413. 
Rhodomela subfusca f. virgata. Transverse sec- 
tion of stem. 80:1. 
between vegetative and fertile shoots. Further, the 
above-mentioned greater thickness on the middle 
of the long shoots is often wanting. When in 
doubtful cases the anatomical structure, which 
according to KJELLMAN seems to offer a very 
good distinction, is taken into consideration one 
finds that this also is not reliable. As a rule the 
anatomical structure in Rh. virgata is as described 
by KJELLMAN (fig. 412 B), but not rarely a more 
or less developed small-celled cortex is to be 
found in the lower part of the long shoots in 
specimens otherwise agreeing with typical Rh. 
virgata. Such a cortex may be found on one 
side of the branch but not of the other (fig. 413), 
or several more or less confluent proeminences 
with similar structure or even a continuous cortex 
all round may be met with. Usually then some 
long shoots are provided with cortex, others not. 
D. K. D. Vidensk. Selsk. Skr., 7. Række, naturvidensk. og mathem. Afd. VII. 3. 58 
