38 
dukte oder um Detritus in der feinsten Form handelt, habe ich mit Hilfe des 
Mikroskopes nicht entscheiden konnen«. Since we now know, that with us in 
the Limfjord and most probably in all waters with dense vegetation, the »plankton« 
is mainly detritus, the matter is placed in another. light; but to make any difference 
between detritus-feeders and plankton-feeders thus becomes in fact impossible. For 
this we should require to find certain species, which were able to filter the detritus 
from the plankton, in order to feed on the latter alone; but according to Raushen- 
plat's tables such are very rare, in Cynthia rustica alone has he sometimes found 
»sebr reines Plankton«, and in Cynthia grossularia sometimes »reines Peridine- 
plankton«; but often there was also much impure plankton and »uukenntliche 
Masse«. It would be better perhaps to distinguish between animals, which take 
their food from the water by filtration and animals which directly feed on 
parts of the uppermost brown layer of the bottom; the result will often be 
very much the same, however, only the method is different. Certain worms, 
Lamellibranchs and Echinoderms certainly take their food from the bottom itself, 
but most of the other detritus-feeders, as many Lamellibranchs, Holothuriaus etc. 
from the water. 
Rauschenplat mentions lastly a group of animals which live on »flesh- 
food«, namely various, probably all, fishes, larger Crustacea, as crabs and shrimps, 
most of the Nereidae and Åsterias rubens, and animals which live on fresh 
plants. Under these are placed Idothea, many Gammaridae, also Littorina littorea 
and Acera bullata; a special division, which lives on small plants, especially bottom- 
diatoms, is formed by Rissoa octona and Cerithium reticulatum. 
In 1909 appeared a work by E. Eichelbaum: Uber Nahrung und Ernåh- 
rungsorgane von Echinodermen. Kiel, 4%, pp. 1—88 (Wissens. Meeresunt. Bd. XI. 
Abt. Kiel), in which the food of the Echinoderms was studied on animals collected 
parily at Kiel partly in the North Sea. Reading through the orderly tables on the food 
contents of the digestive organs we are at once struck by the very large quantity 
of »Bodenmaterial« present in them; he refers none of the Echinoderms investi- 
gated by him to the plankton-feeders. Regarding Echinocardium cordatum, for 
example, whose stomach content is always bottom-material, he writes: »Der Darm 
ist mit Bodenmaterial stets prall angefillt und die Bewohner dieses Meeresbodens 
bilden die Nahrung des Seeigels«; something similar is said regarding the nearly 
related forms. That the bottom-material could of itself be of great importance as 
food, he does not seemed to have grasped; on p. 71 however he says in a sum- 
mary on »Irrigulares«: »Meeresboden und die in ihm lebende Tiere«. 
I would also refer here to a work by E. Ehrenbaum: »Zur Naturgeschichte 
von Crangon vulgaris Fabr.« (Sonderbeilage 3. d. Mitt. d. Sekt. f. Kisten- und Hochsee- 
fisherei. 1890). He has closely studied the food of the shrimp both in the open 
and in stomachs; he finds that the larvae contain »eine breiige Detritus åhnliche 
Masse« — »in der gerformte Theile nicht mehr zu erkennen waren«; later however 
he mentions diatom skeletons in this and that among other things plant remains 
must play a certain role for the larvae. I believe that the larvae must also be 
regarded as detritus feeders. The adult Crangon on the other hand often feed on 
pure mud (»Schlick« he calls it) from the bottom, their stomachs are full of it and 
they have a peculiar taste at that time; at other times they feed on worms, Amphi- 
