Instruction in Pharmacology should be based on a rigid course of required laboratory experiments. The student in the subject must be given every opportunity to observe for himself. The changes produced by a drug in the activities of a tissue, of an organ, and of the entire organism. It is only on such intimate personal experience with the facts that one can reach a rational understanding of the principles of Pharmacology. The directions presented here have been formulated during the growth of the course as presented in the University of Missouri. Under each drug presented there is given a list of experiments chosen with due consideration to the facility with which they may be performed by students. This list is followed by detailed yet brief directions for the execution of the experi ments. An occasional type illustration is given to guide the student in his efforts. It is assumed that the individual student will have time for only a selected number of experiments on each drug, and the plan of the Guide is so arranged as to support the instructor in the assignment and execution of a number of diversified experiments by the average laboratory class.