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bottom is secured by this means, simply because sifting in this 
way more than a small sample of the contents of a full trawl 
would be an insuperable task. 
Another way to secure this microfauna is to skim the upper 
layer from samples taken up by means of Dr. Petersen’s bottom 
grap. Here the upper layer may be had fairly undisturbed, and, 
evidently, it will be possible by this means to get a fair knowledge 
of the quantity of micro-organisms in the upper layer of the bottom. 
More undisturbed this layer is brought up by means of the glass- 
tubes also used by Dr. Petersen for the study of bottom samples. 
These methods may well suffice for the quantitative study of the 
bottom-fauna. But for the naturalist who wants to study these 
organisms from a morphological or classificatory point of view or 
who wants to gain as complete a knowledge as possible of the 
various species occurring im some place, and therefore wants to 
have a large material of the various forms at his disposal, these 
methods are very unsatisfactory. 
The problem of an effective method of catching the micro- 
organisms of the sea-bottom, not for quantitative but for qualitative 
study, has occupied me for some time. While investigating the 
fauna of the sandy beaches of the Danish Coasts (“Biologiske 
Studier over Sandstrandsfaunaen, særlig ved de danske Kyster”. 
Vid. Medd. Dansk Naturh. Foren. Bd. 74, 1921.) I tried to skim off 
the upper bottom-layer in places sheltered from the wave action, 
— e. g. on the large muddy flåts (“Vader”) at Fanø, off the West 
coast of Jutland, and to sift the material through a fine silk net. 
The result proved quite up to my expectations, a very rich fauna 
of small organisms: Nematods, Copepods, Ostracods, Infusoria etc. 
being found to inhabit this layer. Extending fhis study also to 
places, where the bottom was sand, e. g. the extensive sandy flåts 
with Cyanophyceæ off the Southend of Læsø in Kattegat, I had, 
of course, to modify the method, as the net to be used for sifting 
must be too fine-meshed for permitting the sandgrains to pass 
through. The upper layer to about a centimeter’s thickness was 
peeled off and put into a bucket with water, to which was added 
some formalin. It was then all stirred well round and allowed to 
settie. The sand sinking first to the bottom leaves the finer detritus 
and all the minor, lighter organisms floating, while the water is 
