The infections of common colds are always to be found in the nasal passages and become active when the individual is subject to fatigue or indigestion or both. The liability of catching cold is greater when the mucous lining is injured. Nasal douches are injurious and impair the protective ability of the mucous membrane. They should be used only on prescription. A very gentle, warm spray of weak salt and water may be used when the nose is filled with soot and dust. The fingers should be kept from the nose. Handkerchiefs should be frequently changed, or small squares of gauze used and subsequently burned. [Sidenote: Tuberculosis Germs] The germ of tuberculosis is probably conveyed oftenest through the sputum of consumptives, when this sputum has been allowed to dry, has become pulverized and is breathed into the system. All sputum should be burned. It is well to avoid rooms occupied by consumptives who are not careful with their sputum. [Sidenote: Mosquito-borne Malaria and Yellow Fever] Suitable wire netting will guard us from malaria and yellow fever, the infections brought by mosquitoes and flies. The mosquito often carries malaria, and in the tropics carries yellow fever and other diseases. As some one has said: "A yard of screen in the window is better than a yard of crape on the door." The greatest triumph in connection with the building of the Panama Canal was not the engineering but the reduction in the death-rate among the workers, which, on account of these insect-borne diseases, had previously prevented the successful execution of the undertaking. Not only is it desirable to screen from mosquitoes, but to put oil on any body of water where they breed. Even a small puddle can breed millions of mosquitoes. No empty tin cans should be allowed to collect about the kitchen door; they gather rain-water and soon breed mosquitoes. [Sidenote: Typhoid-free Water] We take in many disease germs through food or drink. Every year 300,000 people in the United States enlist under the typhoid banner. To elude the typhoid-germ we need first of all pure water. But when one is in doubt as to the purity of water, it is advisable to boil water in order to destroy possible typhoid germs and other dangerous germs and impurities. Where hygienic water has been used a very large proportion of the deaths from typhoid has been eliminated. Where this is not feasible, it is desirable to use chlorinated lime (ordinary bleaching powder) in the drinking water (one part to 200,000--shake up and leave several minutes). If water of doubtful quality has to be drunk, it should be at the middle or end of a meal when the healthy stomach contains plenty of gastric juice, which to a limited extent has the power to kill germs. It is safer to keep out of swimming tanks that are not filtered or refilled constantly, or chemically purified as by chlorinated lime. [Sidenote: Typhoid-free Milk]