856 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
The absorption of digested matters through the walls of the alimen- 
tary canal in man and other animals is explained as the joint effect of 
dialysis and of a special action of the organs through which the mate- 
rials pass. Considering the body of the oyster as a membranous sac 
(or as a congeries of membranous sacs) containing a more concentrated 
solution and immersed in a more dilute solution, and at the same time 
as a living organism performing its normal functions, the occurrence of 
physical dialysis along with the physiological processes of secretion or 
excretion would be perfectly natural. 
But although the experiments do not show just how much of the loss 
of organic compounds was due to purely physical and how much to 
physiological agencies, it is evident that a large quantity of water was 
carried into the bodies of the auimals and a considerable amount of 
mineral salts was removed by dialysis. 
EFFECT OF FLOATING UPON NUTRITIVE VALUE. 
7. So far as the effect of floating upon the nutritive value of the 
oyster is concerned, the experiments confirm in detail the perfectly 
evident a priori conclusion that with the increase in bulk and weight 
there is no corresponding gain but rather a slight loss of nutrients. 
Hence a given weight or volume of floated oysters will have considera- 
bly less nutritive material than the same quantity of oysters which have 
not been thus treated. According to these experiments, which agree 
with the results of practical experience, the difference would amount to 
from one-eighth to one-fifth or more in favor of the oysters in their nat- 
ural condition. But the removal of the salts in floating would be con- 
sidered by many consumers to improve the flavor of the oysters more 
than enough to make up for the inferiority in nutritive value. It seems 
also to be a matter of common experience that oysters keep better when 
part of the salts have been removed by the dialysis. While, therefore, 
this treatment of oysters is a device practiced by both cultivators who 
float and retail dealers who water them and thus increase the bulk of 
wares sold by bulk, it is not entirely a fraud, since both the flavor and 
keeping quality are often improved thereby. 
5. OYSTERS AS FOOD. 
Yery little is popularly known, and widely varying views are held with 
reference to the value of oysters and other shellfish for food. Although * 
a great deal of scientific research has of late been given to the subject of ♦ 
food and nutrition, these particular kinds of food have been studied but - 
little, and what has been done is slow in getting into print and becoming 
generally known. The lack of popular knowledge of the subject is 
therefore easy to understand. 
