482 



BULLETIN OF THE BUREAU OF FISHERIES. 



experiments were made with very careful technique. The oyster meats were dried at 

 low temperature — some of them in vacuum desiccators — to constant weight and the 

 ether used for extraction was rendered anhydrous by distillation over sodium imme- 

 diately before use. The seeming increase of fat reported for one of the earlier experi- 

 ments may have been due to the difficulty in maintaining ether in an anhydrous con- 

 dition in the moist atmosphere of Woods Hole where the analysis was made. The re- 

 sults given in Table 4 do not show in the amounts of ether extract obtained any regu- 

 larity or any relationship to glycogen. A number of other fat determinations on oysters 

 have been made during the progress of this work. These are not included in this table 

 because glycogen was not determined on the same specimens. In no case, however, 

 did the ether extract amount to more than 3.50 per cent of the dried meats. A series of 

 analyses reported by Atwater " gives higher figures, ranging from 6.50 to 10.97 per cent, 

 with an average of 8.78 per cent for 34 analyses. As those determinations were not 

 made with the use of anhydrous ether, they are hardly comparable with the ones reported 

 in this investigation. 



Table 4. — Comparison op thb Glycogen and Fat Content of Oyster Meats. 



Bxperimeiit No. 



Gly- 

 cogen in 

 ash-free 

 solids. 



Per cent. 

 22.46 

 21. 76 



14. 22 



8.94 

 8.83 



Fat 

 (ether 

 extract) 

 in dried 

 meats. 



Per cent, 

 2.90 

 3.16 

 2.04 

 I- SI 

 2-93 

 I. 19 



Fat in 

 ash-free 

 solids. 



Per cent. 

 3-51 

 3-91 

 3- 16 

 2.28 

 4-32 

 I. 71 



Experiment No. 



21. 

 22. 



27- 



28. 

 29. 



31- 

 34- 



Gly- 

 cogen in 

 ash-free 

 solids. 



Per cent. 

 7-63 

 7-38 

 6.40 

 6.23 

 5-88 

 5-59 

 9. 20 



Fat 

 (ether 



extract) 

 in dried 

 meats. 



Per cent. 

 2-33 

 3. 26 



I. 41 

 2.8s 

 1.72 



Fat in 

 ash-free 

 solids. 



Per cent. 



3-44 

 2- IS 

 4. II 

 2. 72 

 2. IS 

 2.60 



The oysters showing the high glycogen content were the ones which presented a 

 "fat" appearance. Indeed, the two specimens yielding the highest glycogen figures 

 were selected for analysis by practical oystermen and chosen from beds of oysters 

 deemed to be in the best marketable condition. The conclusion that glycogen is the real 

 nature of the "fat" does not rest alone on the results recorded in the preceding tables. 

 During the past two years glycogen determinations have been made on many samples 

 of oysters in coimection with this work. However, only those for which ash and either 

 nitrogen or fat, or both, have been determined also are tabulated here. Of the other 

 specimens it has been noticeable that the higher the glycogen the "fatter" the oysters 

 appeared. Six samples from Lynnhaven Bay, Va., and Narragansett Bay, R. I., con- 

 sidered by the trade to be in good marketable condition, contained glycogen varying 

 from 15.5 to 22.8 per cent of the dried weight and from 20 to 27.9 per cent of the ash- 

 free solids. 



DISTRIBUTION OF GLYCOGEN. 



The distribution of glycogen in the bodies of oysters of average "fatness" was inves- 

 tigated. About 50 oysters were opened immediately after removal from the water, 

 about September 15, when glycogen formation is rapid. All the juice was drained off 



a Atwater. W. O.: "The chemical composition and nutritive value of food fishes and aquatic 'invertebrates," Report of 

 United states Commission of Fish and Fisheries, i8S8. pp. 679-868. 



