78. Several precautions should be observed in purchasing shell fish. For instance, crabs and lobsters should be purchased alive. They are usually shipped on ice so that they will remain in this condition for some time, and they are displayed on ice in the markets for the same reason. Such shell fish should be kept alive until they are plunged into boiling water to cook. Oysters and clams bought in the shell must also be alive when purchased. A tightly closed shell indicates that they are alive, whereas a slightly open shell proves that they are dead. If these two varieties are bought out of the shells, the fish themselves should not be accompanied by a great quantity of liquid. Considerable liquid is an indication that the oysters or clams have been adulterated by the addition of water. Formerly it was the custom to keep oysters in fresh water, as the water they absorb bloats or fattens them. This practice, however, has fallen into disfavor.
79. Shell fish lend themselves admirably to a large variety of dishes, including soups, entrees, salads, and substitutes for meat dishes. They possess a great deal of distinctive flavor, their food value is comparatively high, and, provided they are in good condition and are properly prepared, they are healthful and easily digested. It can therefore be seen that shell fish have much to recommend their use. There is considerable danger, however, in using any varieties that are not perfectly fresh or freshly cooked. In the case of mollusks, or bivalves, much harm has resulted from the use of those which have been grown or bred in unsanitary surroundings. Because of these facts, it is of the utmost importance that great care be exercised in selecting and preparing shell fish.
80. COMPOSITION AND FOOD VALUE OF SHELL FISH.--In composition, the varieties of fish included under shell fish do not differ greatly from fish proper. Most of them, however, contain more waste and less of the food substances than fish, so that their food value is somewhat lower. Table IV will serve to give a good idea of the composition and food value of the several varieties of shell fish, and in studying it, a good plan will be to compare it with Table I, which gives the food value of fish. As will be observed, protein forms a very large proportion of the food substance of shell fish. Also, they contain more carbohydrates than fish, the amount ranging from .4 to 5.2 per cent., which is in the form of sugar. Although this amount is too small to warrant much consideration as a supply of carbohydrates, it is mentioned because it is an interesting fact.
TABLE IV
COMPOSITION AND FOOD VALUE OF SHELL FISH
| Name of Fish | Water | Protein | Fat | Total Carbohydrates | Ash | Food Value Per Pound Calories |
| Clams, removed from shell | 80.8 | 10.6 | 1.1 | 5.2 | 2.3 | 340 |
| Crabs, whole | 77.1 | 16.6 | 2.0 | 1.2 | 3.1 | 415 |
| Lobsters, whole | 79.2 | 16.4 | 1.8 | .4 | 2.2 | 390 |
| Oysters, in shell | 86.9 | 6.2 | 1.2 | 3.7 | 2.0 | 235 |
| Scallops | 80.3 | 14.8 | .1 | 3.4 | 1.4 | 345 |
TABLE V
SEASONS FOR SHELL FISH
| NAME OF FISH | SEASON |
| Clams, hard shelled | All the year |
| Clams, soft shelled | May 1 to October 15 |
| Crabs, hard shelled | All the year |
| Crabs, soft shelled | March 1 to October 15 |
| Lobsters | All the year |
| Oysters | September 1 to May 1 |
| Scallops | September 15 to April 1 |
| Shrimp | March 15 to June 1, and September 15 to October 15 |
81. SEASONS FOR SHELL FISH.--With the exception of clams and lobster, which can be obtained all the year around, shell fish have particular seasons; that is, there is a certain time of the year when they are not suitable for food. It is very important that every housewife know just what these seasons are, so that she will not include the foods in the diet of her family when they should not be used. Table V, which will furnish her with the information she needs, should therefore be carefully studied.
OYSTERS, CLAMS, AND SCALLOPS