THE Comprehensive nature of the subject precludes the possibility of giving a short and precise definition. A late writer on hygiene has given the following definition: "Hygiene aims to make growth more perfect, life more vigorous, decay less rapid, death more remote." Hence hygiene treats of the laws of health; of all those measures which tend to preserve the body in a healthy condition, as well as those which tend to improve the general health. It embraces a knowledge of the factors and conditions which bring about ill health and disease, as well as a knowledge of the methods of preventing disease, and of the measures which tend to fortify and improve the organism.
Health is that condition of the body in which all the various functions are performed normally, and without the manifestation of discomfort in any of its operations. Disease, on the other hand, implies the imperfect performance of one or more of the bodily functions because of the impaired structure of the corresponding organ or organs, and the consequent manifestation of discomfort, either in the part directly affected or in the body generally. There are many factors which may operate in such a manner as to bring about disease. These factors are usually divided into the immediate and remote causes of disease.
The immediate causes of disease may be again divided into three classes, physical, chemical, and vital. The