NATURAL SCIENCES OF PHILADELPHIA. 443 



which consists in placing them for a short time in fresher water 

 than that from which they have been taken. 



Persons who are fond of this animal as an article of food, know 

 how much the " fresh" exceed the " salts" in size and consistency. 

 The "Morris Coves" of this city, while very insipid, are the 

 plumpest bivalve brought to market. On the other hand, the 

 " Absecoms" and "Brigan tines," while of better flavor (to those 

 who prefer salt oysters), are invariably lean compared to their 

 transplanted rivals, as also are the "Cape Mays," though, from 

 some reason, not to the same extent. 



The naost experienced oyster dealers inform me, that the time 

 for allowing the salt oysters taken from the sea-coast to lie out, 

 varies, but is seldom over two to three days. At the end of this 

 time the maximum plumpness is attained, and beyond this, the 

 oyster becomes lean again, besides having lost in flavor. 



It is not possible that the smooth rotundity of the laid-out 

 03'ster can be due to increase of flesh. The time is too short, 

 and the conditions are unfavorable. 



On the other hand, the explanation by dialytic action is easy. 

 During the growth of the oyster on the sea-coast, his tissues are 

 constantly saturated with the ocean brine. On removing this 

 oyster to merely brackish, or to fresh water, the conditions are 

 at once favorable for osmose to be commenced. The fresher and 

 less dense liquid without, permeates inwards more rapidly than 

 the more saline and denser liquids within escape, and the effect 

 is to swell the tissue as a cow's bladder half filled with air and 

 immersed in a vessel of h} r drogen is swollen, or still more nearly 

 like the swelling of a bladder half filled with copper sulphate 

 when immersed in pure water. 



It is worth while to inquire whether means could not be devised 

 to effect this fattening, while yet not depriving the oyster of the 

 salty flavor which is its chief charm to many consumers. Per- 

 haps an immersion in concentrated brine for several days, and its 

 subsequent removal to ocean water, would suffice. As to the 

 value of placing corn-meal upon a pile of 03*sters for the purpose 

 of fattening them, it is obvious that the time is too short. A 

 simple way of ascertaining whether there were or not an actual 

 gain in flesh, would be by taking a hundred or more oysters from 

 a given locality on the sea-coast, drying them at 220 Fah., and 

 ascertaining their average weight, and repeating the process for the 

 same number of like oysters after transplanting. 



