Just one word of explanation is perhaps needed at the outset. Common-sense Biology does not mean anything like that slipshod dealing with miscellaneous phenomena of nature which sometimes goes by the name of Nature Study. It is a course of work systematic and strictly scientific, conducted as truly as any other in the scientific spirit. It presents, however, two points of contrast with special or analytical Biology, in that, whereas, in analytical Biology, a beginning may be made practically anywhere, with any series of facts one may prefer to take first, in Common-sense Biology there is only one right mode of starting, and that of the utmost importance; while, secondly, Common-sense Biology combines some of the characteristics of an art with the ordinary characteristics of a science. COMMON-SENSE BIOLOGY It is this latter form of the science--this science, which is also an art--that we would advocate as essential for the equipment of women. With this view let us examine it further. And first, what is its proper starting-point? Its proper starting-point is accurate instruction concerning the living things with which the student is, or can easily be, brought into immediate practical contact. And, again, in the study of these living things--plants and animals alike--attention is directed first towards the organism in its totality and in its activities--towards function rather than towards structure; and also towards mode of life, relations with environment, and, where possible, towards its use or danger to mankind. Structure will, no doubt, early have to be introduced, but only in its larger details as explanatory of function, for the sake of a better knowledge of the animal or plant as a whole. What are to be the types and examples of organisms studied? This is an important question, and the writer would most strongly urge that the principle of selection should be that of locality; that the student should start with those plants and animals--both wild and domestic--which are to be found within a given radius of the place where she is living and working. The first things to know about are habit, activity, inter-relation and use to human beings. In respect to these, the presence of one organism will react upon others, and therefore no plant or animal within the area should be lightly overlooked. THE IMPORTANCE OF BACTERIOLOGY