of the Fishery Board for Scotland. 



197 



IT.— THE FOOD VALUE OF THE HERRING. 



By T. H. Milroy, M.D., B.Sc, F.R.S.E., Professor of Physiology, 

 Queen's College, Belfast. 



Part II. 



The Herring of the East Coast Of Scotland. 



In my previous paper, published in last year's Report, I dealt with the 

 food value of the herring in the Loch Fyne and neighbouring areas, and, 

 at the desire of the Fishery Board, I have carried out a similar investiga- 

 tion dealing with the fish of the East Coast. The general plan of 

 investigation was the same in the later investigation. In only one 

 important respect did it differ, namely, in the addition of one analysis, 

 that of the coagulable proteids of the muscle of herring. 



It is therefore only necessary to describe this method of analysis, and 

 the reader is referred to the earlier paper for a description of the other 

 methods. 



Under the heading " Proteid " in the analytical tables of the earlier 

 paper the amounts were given as calculated from the total 

 nitrogen of the muscle, multiplied by the "proteid" factor, 6 - 25. 



In this investigation it was thought advisable to estimate the coagulable 

 proteid. 



The method of estimation was as follows : — 



Five grammes of minced fresh muscle were taken and placed in a mor- 

 tar and 5 grammes of absolutely anhydrous sodium sulphate were added. 

 The salt and the muscle were thoroughly mixed together so that the 

 water of the latter might be taken up by the former anhydrous salt. 

 About lOOcc. methylated spirit were then added, and the mixture placed 

 in a flask with a reflux condenser fitted to it. The mixture was then 

 boiled for about three-quarters of an hour to ensure complete coagulation 

 of the muscle proteids. The alcohol was then decanted off and the residue 

 extracted with fresh quantities of boiling distilled water until the wash- 

 ings were free from sulphate. The coagulated muscle proteid, which was 

 then left, was incinerated with sulphuric acid, cupric and potassium sul- 

 phate, and the nitrogen estimated in the usual way by Kjeldahl's method. 

 On multiplying the amount of nitrogen by 6'25 the amount of "coagul- 

 able " proteid was obtained. 



The results of the analyses are given in the following tables, which 

 deal with the several batches of herrings sent to me by the Fishery 

 Board. 



In conclusion, I have given a table collecting the results of the analyses 

 of the muscle of the female fish at various stages of reproductive activity. 

 It was not necessary in this investigation to analyse the ovarian substance, 

 as that was done sufficiently thoroughly in the earlier paper. 



Under the heading " Per average fish " the amounts of the various 

 nutritive principles in the average fish of the series are given after 

 deduction of one-third of the weight to cover the amount of bones, 

 skin, &c. 



