141 
the nearest one being Parker’s Pock, which is over three miles 
distant ; the oysters on the Muddy Marsh bed were very few 
and the mass of shells immense, affording ample surface for 
the attachment of the drifting “ spat,” should there be any. 
But supposing the oysters on the beds to have been so much di- 
minished that they were not sufficient for mutual fecundation, 
the distance and situation of other beds is such as to prevent 
the current from bringing the spermatozoa voided upon them 
to the Muddy Marsh Rocks and there would be, as was noticed, 
an almost entire failure of young. In the same, though less 
degree, would the other beds suffer, the amount of spawn 
voided depending not only upon the number of mature 
“brood” oysters, but upon their distance from each other and 
the spaces separating the beds. This theory is supported by 
the investigations that have been made in England, France 
and Prussia, and almost all opinions coincide that the number 
of young in any spatting season is dependent upon the num- 
ber of “brood” oysters upon the beds. Indeed, it seems so 
self-evident a proposition that it is hardly worth while to exper- 
imentally establish it. It is necessary, then, having accepted 
the theory, to determine what proportion of the oysters should 
be taken off the beds, and what proportion is actually removed. 
As there is no data to my knowledge derived from observa- 
tions made in this country to determine the first of these two 
* desired points, it is necessary to turn to the experience of 
foreign oyster fisheries for guidance, and though the animals 
and the conditions under which they live are not entirely sim- 
ilar, yet some information may be obtained and a line of inves- 
tigation marked out for the future. 
The following is a synopsis of the deductions of Professor 
Karl Mobius, Professor of Zoology in the University of Kiel, 
whose work on the oyster in manuscript was kindly lent me by 
Professor Baird. The observations were made over the Schles- 
wig Holstein oyster beds by government officials from 1730 
to 1852, and were carried on in practically the following man- 
ner. Each bed was dredged over in three or six places, ac- 
cording to its size, and the oysters taken were divided into 
three classes, and carefully counted. The classes were denom- 
