732 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [50] 
At Falmouth, a tub of oysters (1,600) cost, in 1830, 1s.; 1860, 2 to 
24s.; 1863, 4 to 14s.; 1867, 9 to 37s.; and in 1869, 45s. A cask of 
Schleswick-Holstein oysters (700 to 800) was sold, in 187576, to oyster- 
dealers, for 105 marks (about $26.25). 
Fifteen years previous the price was only a third of that sum. By the in- 
corporatien, in 1864, of Schleswig-Holstein in the German tariff union, 
the territory into whose markets the Schleswig-Holstein oysters could 
be brought free of duty was very significantly increased, and at this 
time English oysters were becoming very rare in German markets. The 
political changes in Germany, and at the same time the great increase 
in the consumption of oysters, evidently increased the incentive to a more 
complete fishing of our oyster-beds than in former times, and this ac- 
counts for the extraordinary decrease in the number which arrive at 
maturity to-day, for at the iaspection of these beds in 1869 there were 
found only 282 half-grown oysters for every 1,000 full-grown, and in 
five inspections during the years 1872 to 1876 there were found, on an 
average, only 107 half grown. This is in striking contrast to former 
inspections, where the average was 421 half-grown oysters for every 
1,000 full-grown, as has been shown in chapter 9, p. 35. 
12.—THE CHEMICAL CONSTITUENTS AND THE FLAVOR OF 
OYSTERS. 
The heaviest portion of an oyster is its shell, and this, on an average, 
constitutes about 84 per cent. of the total weight of an ordinary Holstein 
table-oyster. Internally, the oyster is a soft animal; externally, it is a 
stone animal. The dried shells of very old oysters weigh from 250 to 
320 grams. In such heavy, thick-shelled oysters the soft portion is 
generally very poor, and the body-space is smaller than at the time 
when it first attained its complete maturity. From this it follows that 
the edges of the last-formed shell-layers do not pass over those which 
were formed earlier, but lie under them. The principal constituent of 
the shell is carbonate of lime, which forms about 96 to 97 per cent. of 
the whole weight. The shell also contains 1.2 to 1.3 per cent. of sul- 
phate of lime, 0.09 per cent. of phosphoric acid, 0.03 per cent. of oxide of 
iron, and traces of magnesia and aluminum. If these inorganic con- 
stituents of the shell are dissolved in acid, there will remain undissolved 
brownish bits and flakes of an organie substance which has been named 
conchyolin. This contains the elements oxygen, hydrogen, nitrogen, and 
carbon. The left or arched valve of a Holstein oyster contains from 1.01 
to 1.025 per cent. of conchyolin, the right somewhat more, from 1.10 to 
1.15 per cent. This increase in the percentage of conchyolin makes the 
ri ght valve less brittle than the left. 
At times pearls are found in oysters. They generally lie in the mantle, 
but also in the shell-muscle. Pearls are isolated deposits of shell-mate- 
rial. Their chemical constituents are accordingly the same as those of 
