An Apparatus for catching the Micro-F'auna 
of the Sea-Bottom 
Dr. Th. Mortensen. 
Por a long time I have realized the difficulty of securing the 
various small organisms which live in the upper layers of the sea- 
bottom, especially in the fine layer of detritus that covers the bottom 
in places, where it is not swept by the currents. 
The important role that the detritus plays in the ecology of the 
sea has especially been made known through the work carried on 
at the Danish Biological Station by Dr. C. G. Joh. Petersen, 
Dr. H. Bleg vad and Dr. P. Boysen-Jensen (cf. especially the 
Reports from the Danish Biological Station XX, 1911; XXII, 1914 
and XXV, 1918). As a matter of faet the detritus forms the main 
source of food for the immense number of non-predaceous organ¬ 
isms of the sea bottom. 
The researches of the said authors are in the main confined 
to the larger, non-microscopical organisms. We know, however, that 
also minor or microscopical organisms oceur in immense numbers 
on the sea-bottom, where they may be assumed to live especially 
in the uppermost layer, above all in the detritus layer, i. e. in the 
midst of their food. The access to the study of these organ¬ 
isms has hitherto been rather difficult. When the trawl comes up 
filled with bottom material, the small organisms af the upper layer 
are swamped in the mass of mud or sand. Sifting the content of the 
trawl through a sieve of fine silk gauze will permit to get hold of some 
of the small organisms, and this method was especially used during 
the “Ingolf” Expedition at the instigation of Dr. H. J. Hansen, 
and fine results were achieved in that way. I have also used it 
myself on my various expeditions to the tropical seas. But, of 
course, only a very small percentage of the microfauna of the 
