SEA-FISHERIES LABORATORY. 



113 



If we assume that the dried, extracted, ash-free muscle 

 substance is " proteid " in some form or other — an assumption 

 which is a fairly safe one to make — the figures in the column 

 " N " give the percentages of nitrogen contained in these 

 products. It will be seen that they are always less than 16, 

 which is the percentage assumed when one multiplies nitrogen 

 by 6.25 in order to obtain results expressible as protein. 

 Generally speaking, as the percentage of fat increases so does 

 the percentage of nitrogen in the dry, fat-free, ash-free residue 

 diminish ; there are, of course, exceptions to this statement, 

 but on the whole there is the relation suggested between the 

 variation in fat and the quantity of nitrogen in the muscle 

 substance. 



The results of the analyses of Port Erin Herrings are 

 given in the following table. Only the water in the muscle 

 substance was found in the case of the sample of 25.4.1919. 

 It was then assumed that water x oil = 80% of the wet weight 

 of the sample and that the percentage of ash was the same as in 

 that of 14.5.1919. This gives us the results in brackets for the 

 sample of 25.4.1919. 



Manx Summer Herrings , 1919. 



Date. 



Water. 



Oil. 



Proteid. 



Ash. 



Total. 



N. 



25.4.19 



78-3 



(1-7) 



(18-7) 



(1-3) 



(100-0) 





14.5.19 



75-8 



3-7 



18-8 



1-3 



99-6 



15-6 



29.5.19 



69-9 



8-6 



19-5 



1-3 



99-3 



15-4 



12.6.19 



63-6 



17-4 



17-1 



1-1 



99-2 



15-0 



9.7.19 



58-8 



22-4 



171 



1-0 



99-3 



15-2 



31.7.19 



561 



23-8 



16-4 



•9 



97-2 



13-7 



12.8.19 



53-7 



29-7 



14-8 



•8 



99-0 



150 



3-9.19 



55-1 



29-4 



13-8 



•9 



99-2 



150 



20.9.19 



58-6 



26-1 



14-0 



•9 



99-6 



15-5 



The above results are also represented in the graph, 

 Fig. 1, by smoothed curves. The actual percentages are 

 plotted in the figure and it will be seen that the smoothing does 



I 



