30 
ciently systematically, and the determinations given can only be regarded as quite 
provisional. I have not wished to omit them, because no others have been made 
for our waters and because I believe that, in spite of their imperfection they may 
yet be used as an illustration; but they must naturally be used with the greatest 
caution. 
The figures in the table give the number of ccm. of an —y  potassium 
permanganate solution required to oxidize the organic materials, dissolved or suspended, 
in 100 ccm. water. With some exercise the determinations can be made with an 
accuracy of T 0..2—0.3 ccm. of potassium permanganate solution. 
The water-samples were taken with a water-bottle. The number behind 
the locality indicates the depth at which the sample was taken. In a few cases 
the depth of the bottom is also given. 
The first thing that strikes one on considering the analyses given is, all 
the samples contain dissolved organic matter in not so very small 
quantities. It is also of interest to compare these results with the determinations 
made in other waters; for example, Natterer's determinations from the Sea of 
Marmara (1895). Natterer has determined, just as I have done, how many ccm. 
of an my potassium permanganate solution are required to oxidize the organic 
materials in 100 ccm. water. He found that from 2.s—14 ccm. potassium perman- 
ganate solution were used. Taking the average of his determinations we find that 
it amounts to 7.93 ccm.; the average of my determinations for the Limfjord and 
Isefjord (not centrifuged water) is 6.57, thus a figure of almost the same size. 
ÅA comparison with Raben's determinations, which were made after Mes- 
singer's method, is not possible, as we cannot calculate the quantity of the 
oxidized organic matter from the amount of oxygen used. The amount of oxygen, 
namely, differs for the different kinds of organic materials, and the oxidation is 
in many cases incomplete. So far as one can see, however, the results found by 
means of this method are also of about the same size as those found by means of 
the potassium permanganate method. 
Returning now to my own investigations, if we go from the North Sea 
into the Limfjord we find an increase in the quantity of the organie material dis- 
solved in the water, from 3.s in the North Sea to 6.9, 4.s and 4.6 in Thisted and 
Kaas Bredninger. It will be noticed that we have here a complete parallel 
with the bottom-analyses discussed in the preceding section. We saw, 
that the quantity of the organic matter in the sea-bottom also increased, when 
we pass from the North Sea into Thisted and Kaas Bredninger. In the inner 
reaches of the Limfjord, in Louns Bredning and Hjarbæk Fjord, the quantity of 
the organic matter dissolved in the sea-water rises to respectively 5.2 and 5.9, and 
in the eastern part of the Limfjord (off Eegholm) to 9.2. 
There is almost always a steady current of water through the Limfjord 
from the North Sea to the Kattegat. The analyses show, that this current as it 
passes through the Limfjord becomes richer and richer in dissolved organic matter, 
a condition which is also evident by merely observing the colour of the water 
in the Limfjord. In the western part of the Limfjord the colour of the water is 
gray-green, when the weather is calm, in the eastern part of Livø Bredning (about 
at Løgstør) the appearance changes and assumes the brownish colour, which is 
