FOOD-MATTERS IN THE SEA 325 



and the bio-chemist. We want to know next the value of 

 our food matters in proteids, carbohydrates, and fats, and 

 the resulting calories. We have already seen how markedly 

 a fat summer herring differs in essential constitution from 

 the ordinary white fish, such as the cod, which is almost 

 destitute of fat. 



Professor Brandt, at Kiel, Professor Benjamin Moore, at 

 Port Erin, and others, have similarly shown that plankton 

 gatherings may vary greatly in their nutrient value accord- 

 ing as they are composed mainly of Diatoms, of Dinoflagel- 

 lates, or of Copepoda. And, no doubt, the animals of the 

 " benthos," the common invertebrates of our shores, will 

 show similar differences in analysis.^ It is obvious that 

 some contain more solid flesh, others more water in their 

 tissues, others more calcareous matter in the exoskeleton, 

 and that therefore, weight for weight, we may be sure that 

 some are more nutritious than the others ; and this is 

 probably at least one cause of that preference we see in 

 some of our bottom-feeding fish for certain kinds of food, 

 such as polychaet worms, in which there is relatively little 

 waste, and thin-shelled lamellibranch molluscs, such as 

 young mussels, which have a highly nutrient body in a 

 comparatively thin and brittle shell. 



Such investigations of foods and their values seem a natural 

 and useful extension of faunistic work, for the purpose of 

 obtaining some approximation to a quantitative estimate 

 of the more important animals of our shores and shallow 

 water, and their relative values as either the immediate or 

 the ultimate food of marketable fishes. 



Each such fish has its " food-chain " or series of alter- 

 native chains, leading back from the food of man to the 



1 Moore and others have made analyses of the protein, fat, etc., 

 m the soft parts of Sponge, Ascidian, Aplysia, Fusus, Echinus, and 

 Cancer at Port Erin, and find considerable differences — the protein 

 ranging, for example, from 8 to 51 per cent., and the fat from 2 to 

 14 per cent, (see Bio-Chemical Journ., vi, p. 291). 



