attacks may vary from a slight rash to violent gastro-intestinal, circulatory, and nervous disturbances.

Coues[3] has described a rather typical case in a child twenty-one months old and apparently healthy except for some eczema. When the child was slightly over a year old egg-white was given to it, and nausea and vomiting immediately followed. About eight months later another feeding with egg-white was followed by sneezing and all the symptoms of an acute coryza. Extensive urticaria covering most of the body also appeared, and the eyelids became edematous. The temperature remained normal and there was no marked prostration. The symptoms of such attacks vary considerably in different individuals, but usually include pronounced urticaria along with nausea, vomiting, and diarrhea. The rapidity with which the symptoms appear after eating is highly characteristic. Schloss[4] has reported a case of an eight-year-old boy who evinced marked sensitiveness to eggs, almonds, and oatmeal. Experiments in this instance showed that a reaction was produced only by the proteins of these several foods, and that extracts and preparations free from protein were entirely inert. It was further found that by injection of the patient's blood serum guinea-pigs could be passively sensitized against the substances in question, thus showing the condition to be one of real anaphylaxis.

Idiosyncrasy to cow's milk which is observed sometimes in infants is an anaphylactic phenomenon.[5] The substitution of goat's milk for cow's milk has been followed by favorable results in such cases.

In very troublesome cases of protein idiosyncrasy a method of treatment based on animal experimentation has been advocated. This consists in the production of a condition of "anti-anaphylaxis" by systematic feeding of minute doses of the specific protein substance concerned.[6] S. R. Miller[7] describes the case of a child in whom a constitutional reaction followed the administration of one teaspoonful of a mixture composed of one pint of water plus one drop of egg-white, while a like amount of albumen diluted with one quart of water was tolerated perfectly. "Commencing with the dilution which failed to produce a reaction, the child was given gradually increasing amounts of solutions of increasing strength. The dosage was always one teaspoonful given three times during the day; the result has been that, in a period of about three months, the child has been desensitized to such an extent that one dram of pure egg-white is now taken with impunity."

Many other instances of anaphylaxis to egg albumen are on record.[8] In some of these cases the amount of the specific protein that suffices to produce the reaction is exceedingly small. One physician writes of a patient who "was unable to take the smallest amount of egg in any form. If a spoon was used to beat eggs and then to stir his coffee, he became very much nauseated and vomited violently."[9]

The dependence of many cases of "asthma" upon particular foods is an established fact. Various skin rashes and eruptions are likewise associated with sensitization to certain foods.[10] McBride and Schorer[11] consider that each particular kind of food (as tomatoes or cereals) produces a constant and characteristic set of symptoms. Possibly certain definitely characterized skin diseases are due to this form of food poisoning. Blackfan[12] found that of forty-three patients without eczema only one showed any evidence of susceptibility to protein by cutaneous and intracutaneous tests, while of twenty-seven patients with eczema twenty-two gave evidence of susceptibility to proteins.

CHAPTER III

POISONOUS PLANTS AND ANIMALS

Some normal plant and animal tissues contain substances poisonous to man and are occasionally eaten by mistake for wholesome foods.

POISONOUS PLANTS

Poisonous plants have sometimes figured conspicuously in human affairs. Every reader of ancient history knows how Socrates "drank the hemlock," and how crafty imperial murderers were likely to substitute poisonous mushrooms for edible ones in the dishes prepared for guests who were out of favor. In our own times the eating of poisonous plants is generally an accident, and poisoning from this cause occurs chiefly among the young and the ignorant.

According to Chesnut[13] there are 16,673 leaf-bearing plants included in Heller's Catalogue of North American Plants, and of these nearly five hundred, in one way or another, have been alleged to be poisonous. Some of these are relatively rare or for other reasons are not likely to be eaten by man or beast; others contain a poison only in some particular part, or are poisonous only at certain seasons of the year; in some the poison is not dangerous when taken by the mouth, but only when brought in contact with the skin or injected beneath the skin or into the circulation. There are great differences in individual susceptibility to some of these plant poisons. One familiar plant, the so-called poison-ivy, is not harmful for many people even when handled recklessly; it can be eaten with impunity by most domestic animals.

The actual number of poisonous plants likely to be inadvertently eaten by human beings is not large. Chesnut[14] has enumerated about thirty important poisonous plants occurring in the United States, and some of these are not known to be poisonous except for domestic animals.