CHEMICAL CHANGES' OCCURRING IN OYSTERS. 23 



stock but with air agitation, it is seen that they are in very close agree- 

 ment throughout. This shows that the air has little or no effect as 

 such, its effect being only to keep the oysters in motion, so that 

 osmosis will attain a maximum value. The results of Experiments 

 9-A, 10-A, 11, 12, and 15 all agree fairly well, though differences in 

 stock and in methods of handling cause rather large discrepancies in 



some cases. 



SUMMARY. 



1 . The determination of ammoniacal nitrogen by the Folin method 

 is of very little value in estimating the amount of decomposition which 

 has occurred in oysters during preparation for the market, because of 

 the repeated washings to which they are subjected. 



2. For the same reason the determination of amino-acid nitrogen 

 also is useless in estimating decomposition in oysters undergoing 

 commercial treatment, although it is a reliable index of the amount 

 of washing or soaking which the oysters have received. 



3. A marked loss of oyster solids and of ash constituents occurs on 

 washing oysters with fresh water. 



4. Oysters covered with water, but not agitated, are not appreciably 

 affected by osmosis, except in relatively long periods of time. Solu- 

 tion proceeds slowly, but amounts to a large percentage of the solids 

 originally present in the course of two or three days. 



5. If oysters are agitated in fresh water, either by mechanical means 

 or by means of a blast of air, a large increase in volume results in a 

 short space of time, amounting to as much as 35 per cent in 30 min- 

 utes, and to as much as 50 per cent in 90 minutes in these experiments. 

 This increase is believed to be due to osmotic action. As many 

 shucked oysters prepared for the market are washed by this method 

 and sold by measure, it follows that the consumer may be buying 

 added water. 



6. When oysters were washed in unpolluted water of approximately 

 the same salinity as that in which they were grown, no increase in 

 volume was found to occur, the actual loss of nutrients was slight, 

 and the oysters were cleaned as effectually as they were by being 

 washed in fresh water. 



7. The old method of washing oysters on a skimmer with a hose 

 and paddle gives much less osmotic loss, and, therefore, a much higher 

 content of total solids than does the method of washing by a water 

 current and air agitation. 



8. The amount of osmotic distention of which oysters are capable 

 has not been determined. It is at least 50 per cent of the original 

 volume in the oysters under experimentation. 



9. These experiments seem to indicate that there is no connection 

 between soaking and "bleeding" in the commercial package (that is. 



