46 AMERICAN FISHERIES SOCIETY. 



sucli as would be caused by osmose, though there were indica- 

 tions of secretion of nitrogenous matters and, especially, of fats, 

 which are not so easily explained by osmose. This I will speak 

 of later. 



2. The amounts of gain and loss of constituents which the 

 bodies of the oysters experienced may be estimated either by 

 comparing the percentages found by analysis before and after 

 dialysis, or by comparing the absolute weight of a given quantity 

 of flesh and the weights of each of its ingredients before, with 

 the weights of the same flesh and of its ingredients after dialy- 

 sis. For the estimate by the first method we have simply to 

 compare the results of the analyses of the floated and the not- 

 floated specimens. Taking the averages of the two experiments, 

 it appears that : — 



^, , , Before After 



The percentages of Dailysis Dialysis 



Water rose from 77-9 to 82.4 



Water-free substance fell from 22.1 " 17.6 



Total flesh loo.o loo.o 



Protein fell from 10.5 " 8.9 



Fat fell from 2.5 " 1.9 



Carbohydrates &c., fell from 6.9 " 5.2 



Mineral salts fell from 2.2 " 1.6 



Total water-free substance of flesh. . 22.1 17.6 



There was, accordingly, a gain in the percentage of water and 

 a loss of that in each of the ingredients of the water-free sub- 

 stance. This accords exactly with the supposition that during 

 the floating the flesh gained water and lost salts and other in- 

 gredients. 



It will be more to the point to ncjte tlie absolute increase and 

 decrease in amounts of flesh and its constituents — in other words, 

 the actual gain or loss of each, in the floating. Estimates by 

 this method have been made and explained in the detailed ac- 

 counts referred to. They make it appear that 100 grams of the 

 flesh as it came from the salt water was increased b^- floating, 

 in one specimen, to 120.9, and in the other to 113.4 grams. This 

 is equivalent to saying, that the two specimens of flesh gained 



