848 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
experiments. The results of the experiments have a practical as 
well as scientific interest, since they confirm the common explanation 
of the increase in bulk of oysters by “floating,” and show that it is 
essentially a process of watering in which the bulk is increased without 
any corresponding increase, but rather, if anything, a loss of nutritive 
material. 
It is a common practice of oyster dealers, instead of selling the oys- 
ters in the condition in which they are taken from the beds in salt water, 
to first place them for a time — 48 hours, more or less — in fresh or brack- 
ish water, in order, as the oyster men say, to “ fatten ” them, the oper- 
ation being called “floating” or “laying out.” By this process the 
body of the oyster acquires such a plumpness and rotundity, and its bulk 
and weight are so increased, as to materially increase its selling value. 
The belief is common among oystermen that this “ fattening” is due 
to an actual gain of flesh and fat, and that the nutritive value of the 
oyster is increased by the process. A moment’s consideration of the 
chemistry and physiology of The subject will make it clear, not only 
that such an increase of tissue substance in so short a time and with 
such scanty food supply is out of the question, but that the increase of 
volume and weight of the bodies of the oysters is just what would be 
expected from the osmose which would naturally take place between 
the contents of the bodies of the oysters as taken from salt water and 
the fresh or brackish water in which they are floated. 
If we fill a bladder with salt water and then put it into fresh water, 
the salt water will gradually work its way out through the pores of the 
bladder, and at the same time the fresher water will enter the bladder ; 
and, further, the fresh water will go in much more rapidly than the 
salt water goes out. The result will be that the amount of water in the 
bladder will be increased. The bladder will swell by taking up more 
water than it loses, while at the same time it loses a portion of the salt. 
It does this in obedience to a physical law, to which the terms osmose 
and dialysis are applied. In accordance with this law, if a membran- 
ous sac holding salts in solutionis immersed in a more dilute solution 
or in pure water, the more concentrated solution will pass out, and at 
the same time the water, or more dilute solution, will pass in, and more 
rapidly. The escape of the concentrated and entrance of the dilute 
solution will be, in general, the more rapid the greater the difference in 
concentration and the higher the temperature of the two solutions. 
After the osmose has proceeded for a time the two solutions will become 
equally diluted. When this equilibrium between the two is reached the 
osmose will stop. If the sac which has become distended is elastic, it will, 
after osmose has ceased, tend to come back to its normal size, the extra „ ' 
quantity of solution which it has received being driven out again. 
We should expect these principles to apply to the oyster. Boughly t 
speaking, the body of the animal may be regarded as a collection of 
membranous sacs. It seems entirely reasonable to suppose that the 
intercellular spaces, and probably the cells of the body, would beirn- - 
