48 
must rely upon other apparatus than the dredge and trawl; with these it is difficult 
to say what distance they have been dragged over the bottom, nor can we know 
how many animals they have left behind on the distance worked over; the number 
is often many times more than that taken up. 
A dredge was indeed originally constructed so as not to take all that lies 
on the bottom. The special form of dredge, from which all later dredges originated, 
was Otto Frederik Muller's transformed oyster dredge. An oyster dredge always 
has large meshes, in order just to retain the oyster and let all the mud and 
smaller animals pass through, otherwise it would quickly become filled with things 
the oyster fisherman has no desire to have; if it has smaller meshes, we can readily 
capture the smaller animals, but if we reduce the size of mesh to 5 —10 mm. 
square, in order to get still smaller animals, then on soft ground, if it merely 
goes some few cm. down in the soil, it becomes at once filled with bottom- 
material. 
In 1896 already I had constructed an apparatus for the quantitative deter- 
mination of the animal life of the sea-bottom; this is represented in fig. 1, Plate I. 
It was attached to a long pole, which could reach to the bottom in the shallow 
Limfjord, which I especially desired to investigate. It was constructed of thin iron 
plates and could cut 6—8 cm. down into the bottom with its lower, sharp edges, 
which embraced an area of ca. 1 [] foot; the apparatus could be closed by means 
of a line, so that the enclosed bottom-material was dug up by the lower, movable 
parts of the apparatus and partially pressed up into the higher middle part of the 
apparatus; it was closed above by iron gauze, so that the water could escape when 
the bottom-material was pressed in from below. The apparatus worked very well 
in calm weather and in shallow water (6—8 meters); by its means I obtained the 
first insight into the quantity of animallife in the Limfjord. Nothing has ever 
been -published of this work; the main result of counting the animals collected, 
which were separated from the bottom-material by washing through 3 sieves of 
various finenesses, was that many animals were found everywhere in the Limfjord 
where the plaice live, and that the slow growth of the plaice in the western parts ” 
must therefore be due at least in the main to overcrowding; this was sufficient for 
me at that time, but later I had a great desire to investigate these conditions more 
closely. For this the apparatus »bottom-sampler on pole« was not satisfactory, 
partly because it could only be used in shallow water, and partly because the 
weather had to be calm. 
After much experimenting one way and another I came at last to the new 
apparatus shown in the figures 2—3 of Plate I. This is suspended by one line 
and is kept open by an iron rod, which however is set free at the one end, when 
the lead which hangs over its centre falls down on the rod; this occurs when the 
lime is let loose, because the apparatus has reached the bottom. Hauling on the 
line the two halves of the apparatus close like nippers-round the bottom of the 
part surrounding the sharp iron edges. The water in 'the apparatus is pressed 
out through fine metal gauze on the upper side of the apparatus and makes room 
for the bottom-material. This bottom-sampler weighs ca. 40 kg.; by adding weights 
it can be made as heavy as desired. Owing to its great weight it closes with 
great force and the overlocking flanges make it shut very tight. It spans over ca. 

