266 Transactions. 



water bath for three hours; the glycogen was then precipitated with 

 alcohol, washed, and converted into glucose, which was estimated by 

 Fehling's method. 



Fat was estimated by Rosenberg's method — i.e., extraction of the 

 dried material with boiling absolute alcohol and chloroform alternately, 

 with subsequent ether extraction of the material so obtained. 



Protein was calculated from the amount of nitrogen on the assump- 

 tion that the nitrogen formed 16 per cent, of the molecule. It was 

 recognized, of course, that all the nitrogen present was not in the form 

 of protein — in fact, oysters owe much of their value in dietetics to the 

 presence of nitrogenous extractives; on the other hand, they contain 

 much nucleo-protein, or a similar body rich in phosphorus, in which 

 the nitrogen must be under 16 per cent. 



Ash or mineral matter was estimated by incineration, aided by extrac- 

 tion with hot distilled water and subsequent evaporation of the extract. 



The results are given in Tables I and II. 



Table I. — Composition of Stewart island Oysters. 



Edible matter per oyster... 



Dried solids per oyster ... 



Water, per cent. 



Solids, per cent, (by difference) 



Glycogen, per cent. 



Protein, per cent. (N x 6 - 25) 



Fat, per cent. ... 



Salts, per cent. 



Percentage unaccounted-for (assum- 

 ing that II had same glycogen 

 per cent, as I) ... 2"37 P16 3"72 



In the above table it may be observed that samples I, II, and III were 

 obtained early in the season, sample IV at the end, and on comparing 

 these it is evident that a marked deterioration of the oyster occurs by 

 the end of the season : it becomes more watery, glycogen drops to one- 

 seventh of its initial value, the fat diminishes to nearly half, and the 

 extractives are relatively increased. It would be interesting scientific- 

 ally, and would throw a valuable light on what ought to be the limits of 

 the oyster season in New Zealand, if analyses were made at regular and 

 frequent intervals throughout the year. 



Table 11. — Comparison of Percentage Composition of hJried Solids. 



From Table II it will be seen that at their best the New Zealand 

 oysters contain much less glycogen and relatively more fat than the 

 average American oyster. 



♦Calculated from an analysis by Lansrworthy quoted in Hutchison's "Food and 



Dietetics." 



