Idiosyncrasies are found to exist with some persons in regard to special articles of food, and these cannot be readily explained. As a rule, if marked, they extend throughout life, but it is not seldom the case that some people pass through periods when a particular article of food disagrees with them which they have been previously able to eat with impunity. Some are unable to digest milk and are immediately nauseated or made " bilious " by it, while others cannot eat eggs, and yet can drink milk, while some cannot take either. Some can eat the white and not the yolk of eggs. Others, again, cannot eat fat in any form or are unable to digest some one variety of fat, especially hot mutton fat. Some persons acquire a headache whenever they eat butcher's meat in excess. Among the commoner idiosyncrasies of diet are the revolt of the system which occurs from the use of shellfish of all kinds, but especially lobsters, and from strawberries. Fothergill reported the case of a lady who all her life was unable to drink coffee, of which she was very fond, without having diarrhoea from it within an hour or two. Temporary or functional visual disturbances may be produced by alcohol and by indulgence in "high" game or eating spoiled food.

Casey A. Wood, of Chicago, has reported a case of recurrent amblyopia in a physician of fifty-four years of age, who invariably had an attack resulting from the eating of chocolate in any form.

Food idiosyncrasies are not infrequently hereditary, and may affect several members of one family. They are wholly independent of ordinary dyspeptic conditions, and may be present in those whose digestive organs are exceptionally robust.