In the realm of mental phenomena, experiment and measurement have hithertobeen chiefly limited in application to sense perception and to the timerelations of mental processes. By means of the following investigations theauthor has tried to go a step farther into the workings of the mind and tosubmit to an experimental and quantitative treatment the manifestations ofmemory. The term, memory, is to be taken here in its broadest sense, including learning,retention, association and reproduction. The principal objections which riseagainst the possibility of such a treatment are discussed in detail in the textand in part have been made objects of investigation.