10 
be indicated which play the principal part in the composition of the vegetation, 
namely the following: 
Fucus serratus, 
Fucus vesiculosus, 
Laminaria (not in the Limfjord and other fjords), 
Halidrys siliquosa (rare in Limfjord), 
Furcellaria fastigiata (and Polyides rotundus), 
Chorda Filum, 
Phyllophora membranifolia and Ph. Brodiæi, 
Fime, bushy Frlorideae (Polysiphonia species, Rhodomela subfusea, Ceramium 
species, Cystoclonium purpurascens, Brongniartella byssoides). 
Delesseria species (not im Limfjord), 
Desmarestia aculeata, 
Cladophora gracilis (especially in fjords), 
Ectocarpus species. 
These algae are normally attached, usually to stones or on other algae, 
but also to Molluse shells, Zostera and the like. Some of them are annuals, the 
individuals dying off completely, as a rule in the autumn or winter. This is the 
case with Chorda Filum, and it also holds good for several of the finer, bushy 
Florideae (Polysiphonia and Ceramium species) and Ectocarpus species. Others do 
not die down quite completely, there remains a small basal part from which new 
shoots spring up in the following year (Cystoclonium purpurascens, Brongniartella, 
and several others not mentioned here, which however may be of no little impor- 
tance, especially in the littoral zone); the hibernating part is however so small in 
comparison with the part that dies dowu, that these species may for practical 
purposes be placed in the same class with those which are really annuals. 
The most of the above-mentioned algae are however perennial, so that they 
are to be found at all seasons of the year with a complete complement of all 
essential parts of the leaf; in these also, nevertheless, a greater or smaller pårt 
of the leaf is thrown off annually. How large is the part cast off in this 
way, is in most cases very difficult to say. In Laminaria it is easy enough, 
as the leaf is changed every year, whilst the stalk remains, and the leaf contains 
several times more substance than the stalk. In others it is more difficult, and 
in any case the matter has not been closely investigated, but so much at any 
rate can be said, that the fruit-bearing parts, i. e. the parts which contain or 
directly bear the reproductive organs, die after these have been emptied. These 
parts in some are very large in proportion to the total mass, more than half of 
the shoots in question, e. g. in Furcellaria. In others the fruit-bearing parts are 
but small in comparison with the total mass, as in the Fucus species, Halidrys, 
Ascophyllum; but in these not only are the fruit-bearing parts thrown off, but also 
larger or smaller parts of the fruit-bearing shoots.. How much this amounts to 
cannot be said with certainty, as it is certainly different for the separate species 
and for these in different localities, and. for individuals of different ages. In some 
of these species the annual growth will perhaps not amount to the half part, in 
others it will probably exceed this. 
That the annual production of substance is on an average very considerable, 
