Grateful acknowledgment is made to Mrs. Guy Baring, of London, for the loan of her manuscript translation of "Pedagogia Scientifica"; to Mrs. John R. Fisher (Dorothy Canfield) for translating a large part of the new work written by Dr. Montessori for the American Edition; and to The House of Childhood, Inc., New York, for use of the illustrations of the didactic apparatus. Dr. Montessori's patent rights in the apparatus are controlled, for the United States and Canada, by The House of Childhood, Inc.

The Publishers.