Section 4. The department, through its division of research and statistics, shall prepare, with due reference to the requirements of the federal office of education, and annually, on or before May tenth, send to every literary, scientific or professional institution of learning in the commonwealth, and every training school or infirmary, blank forms of inquiry for such statistics as it may prescribe, relative to the number of pupils and instructors, courses of study, cost of tuition and the general condition of the institution or school. The trustees, officers or persons in charge thereof shall annually, on or before June first, return the same with the information required.