178 THE WEALTH OF THE SEA 



a large number of sea-foods were analyzed for their 

 iodine content, using a novel method of analysis by 

 which it was possible to measure accurately the 

 iodine content of foods even when this element was 

 present in amounts as small as one millionth of one 

 per cent. Oysters, clams, and lobster were found to 

 be unusually high in iodine, containing approxi- 

 mately two hundred times as much as beefsteak. 

 Shrimp contain about half this amount, and crabs 

 somewhat less. Marine fishes are also high in iodine, 

 containing fifty times as much as milk or beefsteak. 

 Fresh-water fish contain much less iodine, the 

 amounts found being about the same as in meat. 

 These results indicate the value of marine fish, mol- 

 lusks, and crustaceans in the diet of the inhabitants 

 of regions where goiter is common. It is likely that 

 the reason for the freedom of the Japanese from 

 goiter is the large per capita consumption of fish 

 and other sea-foods. 



Cod-liver oil was the first fishery product to gain 

 recognition as especially valuable in nutrition. For 

 more than a hundred years the therapeutic value of 

 this oil in the treatment of certain diseases has been 

 known to the medical profession, but only for the 

 past fifteen years has it been known that its value 

 lies in its high fat-soluble vitamine content. Butter 

 is one of the most potent common sources of the fat- 

 soluble vitamines, yet samples of cod-liver oil have 

 been found which have two hundred times as high 

 a vitamine content as butter. Because of its fat- 

 soluble vitamines, cod-liver oil is highly effective for 



