The function of the agricultural college library is primarily to serve the interests of the professors and students who compose the college, whereas the mission of the experiment station library is to serve the investigators and scientific workers who constitute the station staff. For the college library to accomplish the best results there should be direct and constant intercourse between the professors and the librarian. The latter should be cognizant of the broad outlines of the courses being given and should be specifically informed of theme work about to be assigned and theses subjects when chosen. If the librarian does not know these things before the call for material comes, it may be very difficult to supply just what is wanted. Even with every care there will sometimes be a conflict of interests, but a system of co-operation between the teaching force and the librarian should reduce these conflicts to a minimum, should work for the benefit of all concerned, and make the library a constantly increasing aid in the process of education. The experiment station library, being designed for the use of scientific investigators, is really a reference collection. It should consist of the records of agricultural investigations the world over and such books of reference in each branch of the station's work as the investigator in charge of that work thinks necessary. The co-ordination of the interests of the two constituencies,--the investigator on the one hand and the teaching force and student body on the other, is one of the most important problems of the librarian of the agricultural library. It is a task which will require his best ability as an administrator, and will be accomplished only by the exercise of boundless patience and unlimited tact, combined with an impartial sense of justice to everybody. Only when the investigator, professor and student each realizes fully that the librarian's chief concern is to be of service to him, will the ideals of the library be realized. The vital concern of experiment station workers and the officers of the agricultural colleges in the library and its activities was evinced by the fact that a session of the Association of American agricultural colleges and experiment stations which met in Columbus, Ohio, November, 1911, was devoted to this subject. Nobody knows better than the workers themselves how useful the library may be to them, and their discussion of different phases of its problems was full of suggestions for the improvement of the service. In the development of the libraries of the agricultural colleges and experiment stations in the various states there have grown up three distinct types of libraries. The first type is the experiment station library which is kept separate from the college library but under its control and which is devoted somewhat exclusively to the use of the station workers. An example of this type of library is found at the State college of Washington.