_General characters of paratyphoid infection._--The symptoms of paratyphoid food infection are varied. As a rule the first signs of trouble appear within six to twelve hours after eating, but sometimes they may come on within half an hour, or they may not appear until after twenty-four to forty-eight hours. Gastro-intestinal irritation is practically always present, and may take the form of a mild "indigestion" or slight diarrhea or may be of great severity accompanied with agonizing abdominal pain. Fever is usual, but is generally not very high. Recovery may occur quickly, so that within two or three days the patient regains his normal state, or it may be very slow, so that the effects of the attack linger for weeks or months. Investigators have noted the occurrence of at least two clinical types of paratyphoid infection, the commoner gastro-intestinal type just described and a second type resembling typhoid fever very closely, and occasionally not to be distinguished from it except by careful bacterial examination. It is not yet clear how these two clinical varieties are related to the amount and nature of the infecting food material. No difference in the type of paratyphoid bacillus has been observed to be associated with the difference in clinical manifestation. Possibly the amount of toxin present in the food eaten as well as the number of bacilli may exercise some influence. The individual idiosyncrasy of the patient doubtless plays a part. While there is still some uncertainty about particular features of paratyphoid infection, a few significant facts have been clearly established: (1) Certain articles of diet are much more commonly associated than others with this type of food poisoning. The majority of recorded outbreaks are connected with the use of meat, milk, fish, and other protein foods. Vegetables and cereals have been less commonly implicated, fruits rarely. (2) In many, though not all, of the cases of paratyphoid meat poisoning it has been demonstrated that the meat concerned has been derived from an animal slaughtered while ailing (_notgeschlachtet_, to use the expressive German term). There seems reason to believe that in such an animal, "killed to save its life," the specific paratyphoid germ is present as an infection before death. Milk also has caused paratyphoid poisoning and in certain of these cases has been found to be derived from a cow suffering from enteritis or some other disorder. (3) There is evidence that originally wholesome food may become infected with paratyphoid bacilli during the process of preparation or serving in precisely the same way that it may become infected with typhoid bacilli; the handling of the food by a paratyphoid-carrier is commonly responsible for this. In a few instances the disease is passed on from case to case, but this mode of infection seems exceedingly rare and is not nearly so frequent as "contact" infection in typhoid. (4) The majority of paratyphoid outbreaks are