CHEMICAL CHANGES OCCURRING IN OYSTERS. 3 



for the washing and chilling of the shucked oysters, and in 1914-15 

 the air-agitation system of washing was in general use in the larger 

 plants. In this system, from 20 to 30 gallons of oysters are placed 

 in a tank of water, ice is added if necessary, and the whole is agitated 

 by means of a blast of air blown in through the perforated bottoms 

 of the tanks. A constant flow of fresh water is maintained. In this 

 way a very thorough washing is secured. With the change in the 

 method of handling, however, the oysterman did not modify the 

 length of time for washing and chilling, which resulted in a great 

 gain in the bulk of the "oysters, due to osmotic action. For in the 

 old method of washing, the oysters remained stationary in the 

 bottom of the tank, their mass was slowly pervious to water, and 

 osmosis could not take place to any extent, whereas in the latter 

 method each individual oyster was constantly exposed to the action 

 of fresh water for a period of from 20 to 30 minutes. As a result, 

 the oysters lost a marked proportion of their soluble constituents, 

 and due to the process of osmosis became greatly distended. 



From the washing and chilling tanks, the oysters were run out 

 upon "skimmers," which are perforated metal tables, to drain. 

 They were stirred about upon the skimmers with metal paddles until 

 they were thoroughly drained, then were run off into cans, which 

 were immediately sealed and stored in a refrigeration room at a 

 temperature of about 33° F. Stock was not usually kept in the 

 refrigerator more than one or two days; in fact, it was usually 

 shipped the morning after packing. 



EXPERIMENTAL WORK. 



METHODS OF ANALYSIS. 



1. Preparation of sample. — The sample of oysters is drained in a 

 colander for two minutes, with gentle shaking or stirring to facilitate 

 drainage, the liquor being discarded. After draining, one pint of 

 the drained meats is ground in a meat chopper, No. 2, using the 

 next-to-finest blade, and thoroughly mixed. The required amount 

 of sample is weighed out immediately, as evaporation causes serious 

 errors in a short time. 



2. Amino-acid nitrogen. — Weigh out 100 grams of the finely- 

 ground oyster meat upon the rough balance, wash into a 500 cc 

 volumetric flask, make up to the mark with distilled water, and 

 shake thoroughly every 10 minutes for 1 hour. Allow to settle, and 

 pour off the supernatant liquid. Upon this liquid the determination 

 for amino-acid nitrogen is run according to Sorensen's method. 1 



3. Ammoniacal nitrogen. — This determination was made by Folin's 

 method, 2 aerating for exactly 2 hours, and using 20 grams of the 



1 Allen's Commercial Organic Analysis, 4th ed., 7 : 262. a Am. J. Physiol., 1903, 8 : 343. 



