In the following year Professor James withdrew from the experimental work, and the conduct of the laboratory was given over to me. In the years which followed, Dr. Arthur Pierce, Dr. J. E. Lough, and Dr. Robert MacDougall were the assistants until three years ago, when the development of the laboratory demanded a division of the assistant functions; since that time Dr. E. B. Holt has been the assistant for the work in human psychology, while Dr. R. M. Yerkes has had charge of the work in comparative psychology. Since from the first I laid special emphasis on research work, a greater number of small rooms was soon needed. In the year 1893, we divided a part of the adjacent lecture-room into four rooms for special investigations, and two years later the larger of the two original rooms was divided into five. As the lecture-room also was finally made part of the research laboratory, we had at last eleven rooms in Dane Hall. The activities of the laboratory, however, went far beyond the research work. We had regular training-courses in experimental practice, and the lecture courses in human and in comparative psychology drew largely on the resources of our instrument cases. Yet the original investigations absorbed the main energy of the laboratory, and demanded a steady expansion of its apparatus. An illustrated catalogue of the instruments has been published as part of the Harvard Exhibition at the Chicago World's Fair. The participation of the students has been controlled by a principle which has characterized our Harvard work through all these years, and distinguished it from the methods of most other institutions. I insist that no student shall engage in one investigation only, but that every one who has charge of a special problem shall give to it only half of his working time, while in the other half he is to be subject in four, five, or more investigations by other members of the laboratory. In this way each research is provided with the desirable number of subjects, and all one-sidedness is avoided. Every experimenter thus comes in contact with a large range of problems and gets a fair training in manifold observations, besides the opportunity for concentration on a special research. It is true that this demands a complicated schedule and careful consideration of the special needs of every research, but it gives to the work a certain freshness and vividness, and banishes entirely the depression which is unavoidable whenever a student is for any length of time a passive subject in one psychological enquiry only. In both capacities, as experimenter and as observing subject, only graduate students have been acceptable. In this way about _one hundred investigations_ on human psychology have been carried on, for most of which I have proposed the problems and the special lines of work, taking care that the research of succeeding years and of succeeding generations of graduate students should show a certain internal continuity.