[17] OYSTER CULTIVATION IN THE NETHERLANDS. 1017 
“ Hendracht,” from some distance north of the Vosmeer Ferry to the so- 
ealled ‘ Nachtegaal”; this applies especially to the whole of lot 38 in the 
“‘ Nachtegaal.” : 
In the above we have endeavored to give a brief sketch of our past . 
and our future activity; and the reader will thereby get an idea of the 
slow progress of our investigations, chiefly owing to the circumstance 
that so far no definite way whatever has been marked out for us. An 
investigation like the present requires time and patience, especially in 
the beginning; it is certain, however, that as we begin more and more 
to reach the firm basis of reliable observations we shall be able to report 
more rapid progress. Once more, briefly put, the questions which we 
must have steadily in view are these: What influence do the tempera- 
ture and saltness of the water have during the period when the larva 
are passed from the mother oyster? Which way does the spat travel 
when passed from the mother oyster, and in what manner is this way 
determined by circumstances directly connected with current, temper- 
ature, and saltness, and how can it be controlled by means of these 
data? What influence do these same circumstances exercise on the full- 
grown oyster. 
As regards the study of those animals which live on the same beds as 
the oysters, as their enemies, parasites, friends, or messmates, we have 
to present the following reports: 
I. InFusortA.—(Report by Dr. J. van Rees.) 
With regard to those infusoria ciliata, which I observed near the 
oysters, I shall for the present confine myself to the following short 
notice. The fauna of the brackish water of the Scheldt, in general, differs 
but little from the fauna of the North Sea, as far as I have learned to 
know it at the Helder, Flushing, and Nieuwediep. 
Besides some few forms described by Claparéde, Lachmann and Stein, 
a few of those varieties were found which Cohn has observed in the 
water of the Baltic, and a description of which he has published ;* but 
his description is far from systematic, and leaves much to be desired, 
especially as regards the illustrations. 
Among the forms of infusoria which I observed, there were the fol- 
lowing: 
Of the group of the HALOTRICH&: a fewsmall varieties of Lacrymaria, 
Amphileptus and Leionotus ; (Amphileptus meleagris Cl. Lachm., which I 
had found in the Helder as a parasite on Carchesium polipinum, did not 
occur here) also Glaucoma scintillans, Cyclidium glaucoma, and Cyclidium 
elongatum Cl. Lachm., erroneously called by Cohn with a new name, 
Limbus velifer. Concerning this last-mentioned kind I must say that 
they do not have one but two pseudo-membranes consisting of very fine 
cilia, which extend from the front part of the animal to the outer side of 
the little oval mouth. 
s ss “ Zeitschrift fiir Wissenschaftliche Zoologie,” Vol. XVI, 1866. 
