75 
measure the quantity of the organisms in the sea, which forms the basis 
of our investigations, is therefore only a logical continuation of the principle of 
Hensen. After many years' work in this field, Petersen has succeeded in con- 
structing a suitable apparatus (bottom-sampler 0.1 m.?) for making quantita- 
tive determinations of the mass and number of the bottom-animals per 
square unit of area. Investigations with the apparatus as figured here have 
been made at many places in Danish waters from the North Sea to the Baltic, 
and tables are given here, based as a rule on 50—100 samples with the bottom- 
sampler, showing the species, number, rough weight and amount of dry 
matter for the bottom-animals. The last factor gives the hest measure for 
the mass of the organic matter in the bottom-fauna per m.?; in the case of the 
Molluscs and Echinoderms the calcareous matter is not included in the amount of 
dry matter. Information is given regarding the quality and quantity of the bot- 
tom-fauna at several places in Danish waters; both vary greatly from one water 
to another, and the fauna is obviously of very different productive capacity. 
At one place the large, old, strongly calcified animals with very small percentage 
of dry matter are predominant; here the production of organic matter is obviously 
but small; the quality is bad. At other places, especially in the fjords, we find 
small, rapidly growing animals in large numbers; here the production is certainly 
large; the quality is good. In the Limfjord (Thisted Bredning) the endeavour 
is being made to carry these investigations a step further forward, partly by 
examining a large number of stations several times in the year, so as to obtain 
more light on the extent of the increase in growth or increment, partly by 
determining the consumption through a study of the amount annually used by 
fishes and predatory animals (whelks, Asterias). Here the fisheries statistics give 
good information, and the daily consumption of food by the plaice is' being deter- 
mined by investigations in nature; each day it digests at least the whole contents 
of its digestive canal. The consumption of the fishes seems but little by compa- 
rison with the total amount of dry matter available; the quantity of the whelks 
on the other hand is greater than that of the fishes. Taking everything into 
account we may conclude, that the bottom-fauna as a whole annually renews its 
own mass, and that in the Limfjord therefore it cannot possibly be satisfied with 
the amount of food, the plankton according to Hensen's, certainly provisional, 
determinations can offer. 
Although we cannot attach too much weight to the figures gained by 
these investigations, owing especially to the various shortcomings — the bottom- 
sampler cannot be used everywhere, e. g. not on stony ground, the investigations 
are not sufficiently numerous, various side-questions not sufficiently studied 
etc. — we ascribe great importance to the whole sequence of ideas which forms 
their basis, and especially to the idea, that the benthos organisms must 
also be investigated quantitatively, so that we may be able to form 
a true picture of the metabolism of the sea. We believe, that such investi- 
gations would very quickly lead to complete and useful results in the smaller, 
enclosed waters; but we are also of the opinion, that quantitative determina- 
tions of the animal life of the sea-bottom in the open waters will become 
necessary sooner or later, if we are ever at all to form any conception of the 
