50 
Mats Weibull 
to be no remarkable variation during the different seasons. However, the mineral 
matters in question seem to increase at the time when the quantities of nitrogen 
and phosphoric acid are at their smallest, i. e. in summer and autumn. In general 
the quantity of salt is somewhat larger in samples from the salty Kattegat than in 
those from the Sound, or from the Baltic, at the same time; cf. the tables III, IV, 
VIII, XII. 
These plants have a fairly large quantity of water in a fresh condition: 
between 72—88 per cent.; in the brown algae it is about 75 per cent. It varies, 
however, in the different parts of the plant and in these too, during different 
seasons. The largest quantity of water is found iu Chorda reaching to 88 per cent. 
In Zostera it is about 82 per cent, in the leaves, more in the large and old than 
in the young and tender ones. The roots and stalks, too, have a larger quantity of 
water; table I. The perennial brown algae, too, contain different quantities of water 
in different parts: it is smallest in the stipe, largest in the young shoots; table XI. 
In all the plants the composition has been calculated on a quantity of water of 15 
per cent., which corresponds to the quantity of water of plants in an air-dried form 
(cf. p. 7). 
The variation in nitrogenous matters has been indicated above, and also 
that it is dependant on the seasons and the composition of the surrounding water. 
The same variation is to be found in albumines as well as in »amides»; it is most 
prominent in a typical sewage-plant like Ulva, least in Chorda. The quantity of 
albumen soluble in pepsine and hydrochloric acid is largest in Ulva (55 per cent.) 
out of all seaweeds examined, moderate in Zostera (40 per cent.), and slight or none 
in the proper brown algae. AscophyUum, however, is remarkable with 2(3 per cent, 
of albumen. 
Just as the nitrogenous matters the crude fat also increases in winter and in 
early spring, and then decreases in summer. The quantity varies between V 2 and 
3 per cent., except in AscophyUum where it may attain to more than 8 per cent. 
In this plant, however, the quantity of fat is largest in summer and less in winter, 
which may be due to the fact that it is here secreted as real fat in order to serve 
as reserve matter, whereas the ether extract in other seaweeds mostly consists of 
dissolvant products. 
All other nitrogen-free matters, the so-called extract-stuffs as well as the cellulose, 
are developed in great numbers in summer but decrease in winter and in spring. 
This is best seen in Ulva (table VIII), but the same rule is evidently applicable of 
all seaweeds. The amount of cellulose is small in all these plants, except in Zostera 
where it may reach to 20 per cent, in summer and about half the amount in spring. 
The quantity of ash constituents is very large and approximately the same in 
all seaweeds. In the perennials, except Laminaria (table XXIV), it is usually less 
in the oldest stipe than in the young leaflike parts (table XV). In all seaweeds, 
except Chorda , it amounts to 10 — 17 per cent.; in the latter it amounts to 22 — 32 
per cent. Of the ash constituents the quantities of potassium and sodium are about 
