CHEMICAL COMPOSITION OF FOOD-FISHES. 
809 
3 of water-free substance, 4.78, is 21.7 per cent, of 22.01, the 
per cent, of water-free substance before dialysis. That is to say, the 
water-free substance fell off by 21.7 per cent, of its amount. Among 
the ingredients of the water-free substance the smallest of these loss 
percentages is in that cf the protein, 17.3 ; the largest in that of the 
ash (mineral salts), 29.9. It is interesting to note that not only the 
extractives but the fats also show larger loss percentages than the pro- 
tein, that of the fats, 26.8, being almost as great as that of the mineral 
salts. 
In the Potomac oysters the loss percentages are a little smaller and 
not exactly parallel, since in this case the loss of the extractives is 
larger than that of the fats. The percentages of fats are, however, so 
very small that these variations may very likely be due in large part to 
errors of analysis. 
It may not be uninteresting to note how these loss percentages stand 
in the liquids and in the whole shell contents as well as in the flesh. 
The calculations in the accompanying table are made in the same way 
as those in the previous table, except that the averages are also given. 
Table 40. — Gain (+) or loss ( — ) of ingredients of flesh, liquids, and total shell contents 
of oysters in floating. 
[Estimated by comparing percentages before and after dialysis and expressed in percentages of the 
percentages of the ingredients before dialysis.] 
In flesh. 
In liquids. 
In shell contents. 
Constituents. 
James 
Potomac 
Aver- 
James 
Potomac 
Aver- 
James 
Potomac 
Aver- 
River. 
River. 
age. 
River. 
River. 
age. 
River. 
River. 
age. 
Water 
+ 6.1 
+ 5.3 
:+ 5.7 
T 0.5 
+ 07 
+ O.C 
+ 3.3 
+ 1.4 
+ 2.9 
Water-free substance .. 
— 21. 7 
— 18. 8 
—20.3 
— 9.1 
—14. 0 
—11.6 
—17.6 
— 8.9 
—13.2 
Protein 
— 17. 3 
—11.8 
—14.5 
+7.1 
+13.2 
+10.1 
—12.1 
+ 2.7 
— 4.7 
Fats 
26. 8 
—17. 8 
—22. 0 
(*) 
(*) 
(*) 
—21. 1 
— 2. 5 
11. 8 
Carbohydrates, etc 
—24.1 
—26.8 
—25.4 
+ 58.3 
+49. 3 
+ 53.8 
—16.5 
—11.3 
—13.9 
Ash 
—29. 9 
-27.2 
-28.6 
—44. 1 
—51.8 
—47.9 
—35. 3 
—38.3 
—36.8 
* The quantities of fats in tbe liquids were so minute that they are omitted in this computation. 
Perhaps the most noticeable change in the composition of the liquids 
in the floating is the increase in the percentage of protein and extract- 
ives. The increase of water and decrease of total water-free substance 
are what we might anticipate, but the considerable gain of protein 
and non-nitrogenous extractives which accompanies the gain of water 
and loss of salts seems, at first sight, rather strange. Although the 
absolute quantities of protein and carbohydrates involved are small, the 
differences which represent the increase are far outside the limits of 
error of analysis. It is, of course, true that the figures above cited rep- 
resent percentages only, and do not tell whether the total amounts of 
protein and extractives in the liquids after floating werelarger or smaller 
than before floating. It is, therefore, possible that the absolute content 
of protein and fats in the liquids may have remained unchanged or even 
grown smaller, but it seems hardly natural to suppose that such changes 
