222 



Appendices to Fifth Annual Report 



than with regard to its digestibility, and it is not at all easy from the 

 chemical point of view to find any reason for the notion, above referred 

 to, that fish is incapable of furnishing a solid meal. For in fish there is 

 a very fair percentage of solid matter ; indeed in the flesh of several 

 species there is usually as much (and often more) solid matter as there is 

 in lean beef. The method of ascertaining the amount of solid matter in 

 a given species of fish is very simple ; but different observers using it 

 sometimes obtain very different results. The method consists in taking 

 the flesh from a number of fish of the same species, freeing it from skin, 

 bone, and tendon as completely as possible, chopping it up thoroughly, 

 and then mixing well the different specimens. A portion of flesh is then 

 taken from the mass so prepared, and after being weighed, is placed in a 

 chamber full of dry air, which is kept at 100° C. by being surrounded 

 with boiling water. It is taken out and weighed occasionally until 

 two successive weighings give the same result. This weight is that of the 

 solid matter in the portion of flesh taken, and from this the percentage of 

 solid matter in the fish is calculated. Table III. shows the results 

 obtained by two sets of observers working at different places and different 

 times. ■ The first column is taken from Professor Atwater's paper ' Zur 

 Chemie der Fische,* and the second is from a paper ' On the Relative 

 Digestibility of Fish Flesh in Gastric Juice,' by Messrs Chittenden and 

 Cummins, f The causes of the divergent results obtained by this method 

 by such competent observers as Professor W. O. At water and Messrs 

 Chittenden and Cummins must be sought for in the fish themselves, and 

 may be such as sex, age, food, and period of spawning, the latter three of 

 which cannot commonly be ascertained in the case of fish from the market. 

 The influence of the spawning season was noticed by Professor Atwater* 

 in the case of salmon, and he found that the male fish had then more solid 

 matter in their flesh than the female, though both had a great deal less 

 than at other periods. The percentages he obtained from the common 

 salmon (Salmo salar) during the spawning season were, male fish 24*66 

 per cent., female fish 21*66 per cent. The average of the two is 23"16 

 per cent., while the average of three trials made at other times was 37 '07 

 per cent. Another condition which has probably a great influence on the 

 amount of solid matter is the degree of fatness. We know that the 

 amount of solid matter in beef is very largely dependent on the condition 

 of the animal in this respect. The fatter the beef is, the less water and 

 therefore the more solid matter does it contain. Lean beef contains about 

 28 per cent, of solid matter, while very fat beef may contain as much as 

 48 per cent. These facts will serve to explain to some extent at least 

 the difference between the amount of solid matter discovered by Pro- 

 fessor Atwater, and that discovered by Messrs Chittenden and Cummins 

 in the same species of fish. It will, however, be noticed, that in spite 

 of the discrepancies many fish usually contain as much solid matter as 

 lean beef, and that one of the commonest and most important of our food 

 fish, namely the herring, contains between 24 and 31 per cent, of solid 

 matter, and is therefore very often more solid than lean beef. 



The nutritive value of foods, however, does not depend so much on the 

 whole amount of solids present as on the amount of those containing 

 nitrogen, the so-called proteids. These substances form the basis of 

 blood and muscle, and are therefore very important in any estimate 

 of the relative nutritive value of foods. In this respect, as in so many 

 .others, fish compares very favourably with beef and mutton. Lean beef 



* Berichte der deutschen chemiscJicn Gesellschaft. Band xvi. S. 1839. 

 t Report of United States Commission of Fish aud Fisheries for 1884, Appendix. 

 Published 1886. 



