810 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
as these could occur in the percentages unless the liquids had received 
protein and extractives from the flesh. 
An explanation of a way in .which such an accession of these ingre- 
dients may have come about has been suggested by my colleague, Pro- 
fessor Conn, who calls attention to the fact that some mollusks, when 
irritated, produce an extremely abundant secretion of mucus or “ slime;” 
so much, indeed, as to sometimes render a small quantity of water' in 
which the animals may be confined quite. sensibly gelatinous. He sug- 
gests that the change to fresh water may induce such a secretion 
of mucus and perhaps of carbohydrates and fats as well, which would 
account for the increase of these substances in the liquids. The obser- 
vation of oyster dealers that “ water always thickens the natural juices 
that adhere to the surface of the oyster and makes it slimy,” accords 
with Professor Conn’s statement. 
I have attempted to estimate the probable amount of absolute gain 
and loss of constituents of the liquids during the floating, by methods 
analogous to those employed for the flesh, as will be explained beyond; 
but the data at hand do not seem sufficient to make the estimate at all 
satisfactory. It may not be amiss to mention, however, that if we 
assume the weight of the shells to have remained unchanged, and 
on this assumption calculate the absolute amounts from the percentage 
composition, the total amounts of liquids appear in one experiment 
to grow larger, and in the other to grow smaller during the floating. 
The same calculation makes the protein increase in one case and de- 
crease in the other. But the changes are very small in all the cases, 
and the impression left upon my mind after this weighing of probabili- 
ties is, that the apparent gain of protein and extractives in the liquids 
is of no very great moment. The reason for saying so much about it is 
its possible bearing upon the estimates of changes in the flesh, as will 
appear beyond. 
ABSOLUTE INCREASE AND DECREASE OF CONSTITUENTS DURING 
THE FLOATING— CHANGES IN FLESH. 
Enough has been said to illustrate the desirability of knowing how the 
actual weights of the shell-contents and of their several constituents 
before and after floating compare. If these data could be exactly 
obtained the actual gain or loss of each would, of course, be made cer- 
tain. The desired determinations could be made with tolerable exact- 
0 
ness by taking a sufficiently large number of oysters from the beds, 
dividing them in two lots of equal number and weight, floating one lot 
and analyzing both. The outlay of labor and money which this plan 
would have required was, unfortunately, larger than the circumstances 
permitted. In lack of such experiments we may, I think, make a toler- 
ably correct estimate of the gain and loss of flesh and its ingredients 
in the experiments already described. 
