The term sanitation or sanitary science is often used synonymous with the term hygiene although there is a difference in their meaning and usage. The term sanitation or sanitary science has been used largely in Great Britain and in this country, although both terms are used in America but with somewhat different meanings. In reality there is a very important distinction between the two terms hygiene and sanitation. Hygiene may be considered the broader term which may be made to include everything relating to health, but more particularly those things which relate to the person. Sanitation or sanitary science relates more to the environmental conditions and their relation to the health of the individual or the community. This distinction is drawn more sharply by reason of the developments along the line of sanitary engineering on the one hand and the biological and physiological developments on the other. Sanitary science has been largely under the supervision and in the hands of sanitary engineers, while hygiene has been almost entirely in the hands of the medical profession. Aim and Function of Hygiene and Sanitation Medically the aim and function of hygiene is to increase the internal resistance of the individual and thus prevent dis-ease and prolong life. The aim and function of sanitation or sanitary science is to improve the environmental conditions and thus prevent dis-ease and prolong life of the individual. Doctor Price gives the aim and function of hygiene as: “The prevention of dis-ease, the prevention of premature death, and the promotion of normal health of individuals and the community by the removal of the causes of dis-ease, destruction of the causes, improvement of the environmental conditions, and by the increase of the vital resistance of the individual and members of communities.” The premise here is correct, but the conclusions as to the methods which are to be used in accomplishing the desired end are erroneous. Internal and External Cleanliness There is a distinction between internal cleanliness and external cleanliness. It is a mistaken idea that because the external is clean, the internal will be correspondingly clean. Cleanliness is absolutely essential to health, but by this we mean internal cleanliness. There must be external cleanliness also, but perfect external cleanliness will not necessarily result in perfect health.