814 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
When the oysters, with their tissues presumably impregnated by the 
salts of the water in which they hav$ lived, were placed in fresher 
water, their bodies gained water and lost not only salts but fats and 
carbohydrates also. The gain of water and loss of salts is naturally 
explained by the outflow of the more concentrated and inflow of dilute 
solution of salts in which the dialysis consists. I find it difficult to 
explain the loss of so much fats and carbohydrates by metabolism and 
discharge of metabolized products, nor does it seem natural to suppose 
that carbohydrates and fats would be dialyzed out of the body so much 
more rapidly in the brackish water than in the salt water. These con- 
siderations and the fact that mollusks excrete considerable quantities 
of gelatinous matters lead me to the conclusion expressed above, that the 
escape of fats and carbohydrates must be due largely if not entirely to 
processes independent of osmose. Of course, small quantities of fats 
and carbohydrates must have been consumed in the ordinary process of 
metabolism, but it is hard to believe that this could explain any con- 
siderable part of the loss observed. 
EFFECT OF FLOATING- UPON THE COMPOSITION OF THE TOTAL 
SHELL CONTENTS OF THE OYSTERS. 
To compare the nutritive values of the oysters before and after float- 
ing, the liquid as well as the solid portion of the shell contents must 
be taken into account. The foregoing statements of changes in compo- 
sition in floating apply mainly to the flesh. The data suffice for only an 
approximate estimate of the changes in the liquids. The difficulty in 
the computation is the lack of exact information as to how much of the 
liquid portion escaped in the floating. The oystermen say that the ani- 
mals sometimes open their valves considerably while they are on the 
floats. This would of course give the water some opportunity to wash 
away the liquid contents of the shells, but the figures here given seem to 
me to imply that the quantity thus removed can not be very great. 
An attempt to compute the changes in the composition of the total 
shell contents might be made by assuming the weight of the shells to 
be unaltered in the floating. 
Table 42 may be worth inserting here, though I do not regard it as 
accurate, since the shells would be apt to lose weight by the washing 
off of adhering matters and otherwise in the handling and floating. In 
each case the protein seems to be slightly increased by the floating, but 
it is evident that we shall have to assume only a very small loss of 
weight of the shells to makedhe figures for the protein the same after as 
before floating. This would give, in each case, a very small loss of fats 
and extractives, a considerable loss of mineral matters, and a large gain 
of water, which is exactly what would be expected, These computa- 
