=Cause and Modes of Communication.=--While the typhoid germ is always the immediate cause, yet it is brought in contact with the body in various ways. Contamination of water supply through bad drainage is the principal source of epidemics of typhoid. Before carefully protected public water supplies were in vogue in Massachusetts, there were ninety-two deaths from typhoid fever in 100,000 inhabitants, while thirty-five years after town water supplies became the rule, there were only nineteen deaths for the same population. Whenever typhoid is prevalent, the water used for drinking and all other household purposes should be boiled, and uncooked food should be avoided. Flies are carriers of typhoid germs by lighting on the nose, the mouth, and the discharges of typhoid patients, and then conveying the germs to food, green vegetables, and milk. Cooking the food, preventing contact of flies with the patients, and keeping flies out of human habitations becomes imperative. Milk is a source of contagion through contaminated water used to wash cans, or to adulterate it, or through handling of it by patients or those who have come in contact with patients. Oysters growing in the mouths of rivers and near the outlets of drains and sewers are carriers of typhoid germs, and, if eaten raw, sometimes communicate typhoid fever. Dust is an occasional medium of communication of the germ. It is probable, however, that the germ always enters the body by being swallowed with food or drink, and does not enter through the lungs. There is little doubt on this point. Ice may harbor the germ for many months, for freezing does not kill it, and epidemics have been traced to this source. Clothing, wood, utensils, door handles, etc., which have been contaminated by contact with discharges from patients, may also prove mediums of communication of the typhoid germ to healthy individuals. Typhoid germs escape from patients sick with the disease chiefly in the bowel discharges and urine, sometimes in the sweat, saliva, and vomited matter.