Lobsters, crabs, and shrimps, although they constitute a wholesome food, when absolutely fresh, for those in health, should never be admitted to an invalid dietary. They are all scavengers of the sea, and crabs not thoroughly cleaned or imperfectly cooked may be poisonous from contamination with putrid matter, although their own flesh is good. Soft-shell crabs are by no means always "soft" when eaten, and their shells furnish a large bulk of indigestible residue, which may prove irritating. I recall one fatal case of appendicitis caused by them.

Lobsters are highly poisonous to some persons even when fresh, and especially if eaten with other food they may excite nausea, vomiting, and even gastro-enteritis. In others they may cause urticaria or aggravate existing skin eruptions.

Persons who live at a distance from the seashore are apt, in making occasional visits to seaside resorts, to gratify a fondness for crustaceans, fish, and shellfish food by an excessive indulgence in "shore dinners," which result disastrously with stomachs unaccustomed to such diet; but the evil effects are fortunately temporary.

Shellfish

Oysters, clams, and mussels are very nutritious food, and the former at least, when fresh and when eaten raw or properly cooked, are an excellent invalid aliment. Oysters can often be digested earlier than meat in convalescence from fevers, and in many forms of gastric disorder.

The "soft part" of shellfish is formed chiefly by the bulkier liver, while the tough, harder portion is mainly the muscle which attaches the animal to its shell. This muscle is coagulated and rendered tougher by all forms of cooking; hence raw oysters are more tender and digestible than if stewed or broiled. In oysters the liver is relatively larger and more nutritious than in clams. In recommending oysters to invalids it is always best to allow only the soft parts to be eaten, and when this rule is observed they may be cooked in a variety of ways - by stewing, broiling, roasting, or "panning," and steaming - but they should never be fried for the sick.

Both oysters and clams have the advantage that they are very generally liked, and they make a pleasant variety of food to relieve restricted diets. They impart an agreeable flavour to milk and broths. It is customary to forbid their use by diabetics, on the ground that their livers contain glycogen. Clam juice or plain clam broth is almost specific for some forms of vomiting, especially seasickness. It may be tried in the vomiting of pregnancy, and may be retained when beef juice and milk are not. It is mildly stimulating to the gastric mucous membrane, and slightly nutritious and laxative. It is best obtained fresh, but very good canned or bottled preparations of it are made which keep pure indefinitely. It may be taken either hot or cold with a little Cayenne pepper half an hour before a meal. It seems to have an invigorating effect upon the stomach, and promotes the appetite.

Mussels are less commonly eaten in this country than in England and some parts of Europe. They belong in the same category with oysters and clams, and the remarks just made in regard to the latter apply to them as well. There is a form of poisoning by mussels which is exceedingly dangerous and sometimes fatal. (See Poisoning by Shellfish).

In some persons shellfish, like crustaceans, produce skin eruptions, such as urticaria, or aggravate existing eczema.