35 
organic matter«; thus a great deal of detritus was also found here. He mentions, 
that he could fish the same diatoms in quantity with the pelagic net in the surface 
waters; but as he does not give the names of these, it is impossible to determine 
whether he has really found pelagic diatoms in the stomach of the oyster or not. 
In shallow water there does not always seem to he sharp boundaries between the 
pelagic diatoms and those living at the bottom. 
Lotsy's view of the small importance of detritus for the oyster, seems to 
have also influenced other American investigators.  H. F. Moore (R. U. S. F. C. 
1897, rep. 1903) thus writes p. 318: »The food of the oyster consists entirely of 
minute animal and vegetable organisms and small particles of organized matter« ; 
but in 1907 »Survey of oyster bottoms in Matagorda Bay, Texas« (Bureau of 
Fisheries document No. 610, 1—86 pp.) he only mentions the diatoms and small 
organisms found in the stomachs of oysters, and not at all the »small particles of 
organized matter«. He figures the commonest of these on 3 Plates; most of them 
belong to the genera Coscinodiscus, Melosira, Synedra, Navicula, Pleurosigma, and 
also Prorocentrum micans. Nearly related or identical forms are found in the 
oyster of the Limfjord; true plankton forms thus also seem rare in the 
stomachs of the American oyster. Moore however has made some very 
careful, quantitative determinations of the quantity of these organisms, both in the 
water and in the oyster and writes on p. 30, that the most surprising thing was, 
the small amount of food consisting of such organisms he found in the oyster: 
— — »the average stomach content of all oysters examined to be about one-eighth 
cubic millimeter, less than one-tenth the volume of the head of an ordinary pin«. 
It would be difficult to wish for a better proof, it seems to me, that it is not 
these small organisms which constitute the chief food of the oyster. Nor does 
Moore seem entirely satisfied with the result of his investigation. He has later 
continued his work on this subject, in order to determine the quantity of diatoms 
in the stomach contents of the oyster (Bull. Bureau Fish. Vol. XXVIII 1908 [1910]; 
but he has not yet come to any definitive result. 
I may also just mention, that the study of the dissolved organic matter 
in the sea-water had previously been considered in connection with the food of 
the oyster, before Pitter in recent years brought it forward again. Lotsy loc. 
cit. investigated the water in which the oysters lived for dissolved organic material, 
but he states that scarcely a trace of this was found in the many chemical analyses 
made; he therefore attaches no importance to this matter. 
The experts of the Dutch Government seem to have laid a great deal of 
weight on the evidence brought forward by Redeke, that it is the bottom-forms, 
and thus the ground, which is of the greatest importance for the nourishment 
and growth of the oyster; and it was certainly of importance to show, that what 
is usually called »plankton« was not the principal food of the oyster; but soon 
new inexplicable factors appeared. Thus, the oysters can live on large stones or 
rocks far above the bottom, i. e. they are not bound to the diatoms of the 
bottom or its detritus. Both in Scandinavia and Italy (Fusaro) the oyster is 
found to feed hanging in the water on iron boxes and the like; Otto Pettersson 
in Sweden and Helland-Hansen in Norway (Intern. Rev., Bd. I, pp. 353—73, 
