SEA- FISHERIES LABORATORY. 273 



used will not alter the relative values of the proteid throughout 

 the year, but is certain to affect the amounts of carbo-hydrates 

 obtained by difference, and may explain, in part, the higher 

 percentages of carbohydrates so obtained, and the corresponding 

 glycogen estimations, in those samples where the latter were 

 taken. Undoubtedly the percentage of nitrogen in mussel 

 proteid is not constant. 



The amount of proteid rises throughout the season from 

 the spawning time in early spring, until the eve of the next 

 spawning. There is a slight depression about February in 

 both years, which seems to occur, however, in conjunction 

 with a fall in general body weight. There seems little doubt 

 that, on the whole, there is an increase up to the time of 

 spawning. 



From May the proteid percentage in the dry-ash-free 

 substance slowly falls until September and October, and then 

 rises again to a maximum in the following March. Since the 

 actual amount of proteid is increasing when the percentage 

 depression shows itself, this increase is obviously not pro- 

 portional to the rest of the tissue during September and 

 October, when there is a rapid formation of carbohydrate 

 material. 



Carbohydrates. 



The carbohydrates differ materially from the proteid and 

 fat as regards their variation throughout the year. There is 

 a slow but steady rise up to the months of September and 

 October, a tendency to form a second maximum in December 

 of both years, and then a rapid decrease until March. The 

 percentages of carbohydrate in the dry-ash-free substance 

 shows essentially the same variations, and in the first year 

 the percentage value rises again up to the spawning in April. 

 The relative abundance and stability of glycogen in the mussel 

 have been referred to in the previous paper, and the conclusions 

 s 



