Every improvement in surroundings means improvement of the chances of survival of the race. In the spring of 1913 the health department and street-cleaning department of the city of New York cooperated to bring about a "clean up" of all filth, dirt, and rubbish from the houses, streets, and vacant lots in that city. During the summer of 1913 the health department reported a smaller percentage of deaths of babies than ever before. We must draw our own conclusions. Clean streets and houses, clean milk and pure water, sanitary housing, and careful medical inspection all do their part in maintaining a low rate of illness and death, thus reacting upon the health of the citizens of the future. It will be the purpose of the following pages to show how we may best care for our own bodies and how we may better the environment in which we are placed. REFERENCE BOOKS ELEMENTARY Hunter, _Laboratory Problems in Civic Biology_. American Book Company. Bailey, _Plant Breeding_. Macmillan and Company. Harwood, _New Creations in Plant Life_. The Macmillan Company. Jordan, _The Heredity of Richard Roe_. American Unitarian Association. Sharpe, _Laboratory Manual_, pp. 64-72, 345-347. American Book Company. ADVANCED Allen, _Civics and Health_. Ginn and Company. Coulter, Castle, East, Tower, and Davenport, _Heredity and Eugenics_. University of Chicago Press. Davenport, _Heredity in Relation to Eugenics_. Henry Holt and Company. De Vries, _Plant Breeding_. Open Court Publishing Company. Goddard, _The Kallikak Family_. The Macmillan Company. Kellicott, _The Social Direction of Human Evolution_. Appleton Company. Punnet, _Mendelism_. The Macmillan Company. Richards, Helen M., _Euthenics, the Science of Controllable Environment_. Walter, _Genetics_. The Macmillan Company. XVIII. THE HUMAN MACHINE AND ITS NEEDS _Problem.--To obtain a general understanding of the parts and uses of the bodily machine._ LABORATORY SUGGESTIONS _Demonstration._--Review to show that the human body is a complex of cells. _Laboratory demonstration_ by means of (_a_) human skeleton and (_b_) manikin to show the position and gross structure of the chief organs of man. Man and his Environment.--In the last chapter we saw that one factor in the improvement of man lies in giving him better surroundings. It will be the purpose of the following chapters to show how man is fitted to live in the environment in which he is placed. He comes in contact with air, light, water, soil, food, and shelter which make his somewhat artificial environment; he must adapt himself to get the best he can out of this environment.