710 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [28] 
lated upon them, and transferred to fresh ponds, if they would be kept 
healthy. In these feeding-ponds the oysters spawn well, and at times, 
when there are any objects of attachment free from mud, such as stones, 
shells, and pieces of wood, the young oysters become attached, but they 
do not mature into marketable oysters. Oyster breeders, after three 
hundred years of practice in rearing young bank-oysters in the mud of 
feeding ponds, have not as yet been able to transform the oyster into a 
mussel which can live and propagate in the mud. The breeders of 
Marennes and La Tremblade have been able to change the color and 
flavor of mollusks, but they have not been able to give the oyster a foot 
for the purpose of locomotion. Along the German coast, in the East 
Sea, the sea-bottom, over many extensive tracts, is firm, and also free 
from mud. ‘These places possess, then, in this respect, one of the most 
important conditions for the successful formation of oyster-beds. Yet 
several attempts to plant oysters in the Baltic have proved entire fail- 
ures. In 1753, 1830, and 1843, oysters were planted along the coast of 
Pomerania. The last of these attempts was made by a company, of 
which the Kings of Prussia and Hanover and the Prince of Putbus were 
members. Fifty thousand oysters, taken in the northern portion of the 
Cattegat, near Frederikshavn, were placed, on the 6th and 18th of 
April, 1843, in the waters southeast of the island of Riigen, near Greifs- 
walder Oie. ‘Two years later, investigations showed that they were all 
dead, since not a single living one could be foand. The much talked-of 
attempt at oyster-breeding by Coste gave a new impulse to the question 
of planting oysters inthe Baltic. In the Bay of Kiel, on the south coast 
of the island of Laaland, in the neighborhood of Korsér, and in the Isef- 
jord, on the coast of the island of Seeland, mature oysters were planted, 
upon apparently suitable ground, but the desired result was not attained 
in either place. The water of the Baltic is not salt enough for the propa- 
gation of the oyster. East of the island of Riigen the water at the bot- 
tom contains only 1 per cent. of salt, and near the surface still less, 
since the rivers bring in much fresh water. West of Riigen, south from 
the Great Belt, to near the coast of Mecklenburg, the water at the bot- 
tom contains indeed as much as 3 per cent. of salt, but here also the 
surtace-water everywhere contains a less degree. The young oysters, 
as soon as they had left the mother oysters, would then ascend to the 
surface, and thus come into water which throughout the entire southern 
portion of the Cattegat contains less than 2 per cent. of salt, while they 
need water with at least 3 per cent. of salt. This I infer from the 
fact, that. such a degree of saltness is to be found at all places along 
the European coast where natural oyster-beds exist. There are two 
other conditions of the Baltic besides the low percentage of salt, 
which certainly hinder the growth of the oyster—the long-continued 
low temperature of winter, and the lack of regular tidal-currents; for 
in the North Sea, where there are strong and regular tidal-currents, 
the oyster, which is a stationary animal, will receive daily a greater 
