of the Fishery Board for Scotland. 85 
MetHops or ANALYSIS. 
It was impossible to adopt many precautions which might have been 
desirable, owing to the necessity for carrying through the analysis as 
quickly as possible. 
Such estimations as these of the perceutage of water in the muscles and 
reproductive organs cannot be carried out in such a way as to absolutely 
prevent loss of weight from any other cause than the removal of water. 
(1) Water percentages.—The skin was removed, then as much of the 
the muscular tissue as could be conveniently obtained was minced up 
extremely fine by being passed through a mincing machine. 
Specimens were taken between watch glasses and dried in a warm oven 
at a temperature between 60°-70°C., under conditions where oxidation 
was prevented as far as possible, the final drying being carried out in 
vacuo. 
The same procedure was adopted in the case of the reproductive organs. 
(2) Nitrogen and Phosphorus estimations.—It was of course necessary 
to estimate the amount of nitrogenous material in the muscles and 
genitalia, and it was also thought advisable to estimate the amount of 
phosphorus. 
The total nitrogen was estimated in a small portion of muscle and also 
in a similar quantity of ovary or milt respectively, the method that was 
adopted being that of Kjeldahl. 
For purposes of convenience the numbers for the total nitrogen are not 
given in the tables, but are converted into terms of protein by multiplying 
the amount of the total nitrogen by the usual factor, 6°25, This is, of 
course, simply a matter of convenience, some of the nitrogen being present 
in other forms than protein. As, however, by far the most important 
nitrogenous constituent in the muscles and genitalia is the protein, 
probably not more than 2 per cent. of other nitrogenous constituents 
being present, it is sufficient to state the amounts of total nitrogen in 
terms of protein. 
The phosphorus was estimated in a portion of the fluid obtained after 
incineration by the Kjeldahl method. , 
The fluid was rendered ammoniacal, then acidified with nitric acid, and 
the phosphate then precipitated by ammonium molybdate. The phospho- 
molybdate precipitate was subsequently dissolved in ammonia, and the 
phosphate precipitated by magnesia mixture. The triple phosphate was 
then received on an ash-poor filter paper, washed, dried, and incinerated. 
It was then weighed and the weight of the Mg, P.O, was then calculated 
in terms of P,O,, and given as such in the tables. 
(3) Fat. he finely powdered dried material (muscles or genitalia) 
was placed in a Soxhlet filter paper tube and extracted with ether in the 
usual way for about 36-48 hours. Only about 3-4 grammes of the 
dried material were taken, so that the extraction ought to have been fairly 
complete. The fat was freed from ether and weighed in the usual way. 
In the tables the amounts of proteid, fat, and P, O; are given in two 
forms, first, in grammes per 100 grammes fresh muscle and fresh ovaries 
or milt ; secondly, in terms of grammes in total fresh muscle or genitalia 
respectively, as calculated for the average fish of the batch under 
examination. 
It was thought advisable not only to give the percentage amounts of 
proteid, fat, and P, O;, but also the absolute amounts in the muscles and 
genitalia respectively of the same fish. The weight of the muscles of the 
fish was obtained roughly by deducting } of the total weight, this 
fraction being supposed to cover the weight of the head and bones. 
