of ihe Fishery Board for Scotland. 15 



Water. — From this table we see that the percentage of water found in 

 fish is greater than in beef, mutton, and pork. In the mackerel group 

 the average is 72, in the haddock group it is between 80 and 85 

 per cent. 



Proteids. — With regard to proteids the lotal quantity present under 

 the various headings is fairly constant, and varies little in the different 

 meat foodstuffs. But there is some difference as regards the variety of the 

 proteids present. Tn fish, from 4 to 5 per cent, of the proteids consist of 

 the albuminoid gelatine-yielding collagen, which is convertible by boiling 

 with water or treatment with acids into gelatine. There is also much 

 less haemoglobin or allied colouring matter in the flesh and blood of fish 

 than in meat, which accounts for the white colour usually characteristic 

 of the former. The distinctive colour of the salmon and some other 

 varieties of fish is usually due to fatty animal pigments of the lipochrome 

 series, which are not of a proteid nature. Fish are also poorer in 

 extractives, the chief of which are creatin, creatinin, and xauthin. To 

 the presence of these amido-bodies in meat is due the well-known 

 stimulating effect of meat extracts and beef-tea, which, possessing little 

 actual food value, act as a stimulant through the nervous system in a 

 somewhat analogous manner to tea and coffee. Hence fish, through its 

 gelatine-yielding collagen, is excellently suited for soup-making, but 

 because of the absence of extractives does not make good tish-tea. 



Fat. — The amount of fat present sharply divides the mackerel group 

 from the haddock group. The former are spoken of as fatty or oily fish, 

 the latter as lean fish. Halibut and mackerel contain about 5 per cent., 

 herring 8 per cent., salmon and turbot 12 per cent., and eel 18 per cent., 

 whereas none of the fish, in the haddock group have more than 2 per 

 cent, of fat. 



Hence the constituents fat and water appear to form a sort of inverse 

 rntio — the more of the one present the less of the other. This also holds 

 for the other flesh foods. The fish in the haddock group are compara- 

 tively free of fat, but contain a much larger proportion of water. In 

 the mackerel group the proportions of fat and water are not so materially 

 different from those which exist in other flesh foods. 



It has been supposed that not only is the characteristic flavour of 

 different kinds of fish due to the presence of certain constituents in the 

 fat, but that also the proneness of fish to early decomposition may be 

 attributable to the same cause. The former statement may be true, but 

 it has to be admitted that the higher members of the fatty acid series, 

 such as palmitic and stearic acid, have very little smell. The latter 

 supposition is hardly in accord with known facts. The fat of fish is of a 

 soft oily nature, because it contains more triolein, which is liquid at 

 ordinary temperatures, and less tripalmitin and tristearin, which are solid 

 at ordinary temperatures, than the fat of mammals. But the fatty acids, 

 such, as palmitic and stearic, which are saturated compounds, and oleic 

 acid, which is an unsaturated compound, are both alike very stable com- 

 pounds, and are not readily broken up except by strong physical and 

 chemical agents. 



Inorganic Constituents. — The inorganic salts in fish exceed that found 

 in mammalian foodstuffs and contain more phosphate salts. If the 

 average quantity found in the latter be taken as 1, that found in fish 

 averages from 1*5 to 2 per cent. 



Hence when we compare the edible portion or pale muscle of fishes 

 with the red muscle of mammals, and find that the former has usually 

 less fat and much more water, that the tissues are slightly less vascular 

 and have a looser texture, we are led to conclude that these characters 



