consultants in connection with a number of the investigations. The follow-
ing assistants performed essential ratings and computations: Margaret Ash-
ton, Sylvia A. Dyck, Wallace Friesen, Guney Kozacioglu, Richard Lawless,
William LeCompte, Eleanor Hall Mikesell, Edwin Willems, Karl Zangerle,
and Harold Zender.

The authors of particular chapters acknowledge special obligations to
these persons:

ARTHUR J. DYCK (Chapter 5). Dr. J. S. Kounin provided helpful ad-
vice and stimulation during the early stages of the research, and Dr. C. L.
Fawl contributed substantially to the study by means of his cogent criti-
cisms, his encouragement, and his assistance in marking agreement checks.
An indispensable aid was Sylvia A. Dyck who shared the tasks of analyzing
and recording data.

CLIFFORD L. FAWL (Chapter 6). The influence of Professor Martin
Scheerer on the nature of the study is gratefully acknowledged, as is, also,
the contribution of Arthur J. Dyck to whom the author is immeasurably
indebted for the generous performance of services both big and little.

ROGER G. BARKER, LOUISE SHEDD BARKER, and MAXINE SCHOGGEN
(Chapters 7 and 8). The studies profited greatly from the co-operation of
Mr. F. Barraclough, Mr. R. Oliver, Mr. C. M. Turner, Mr. H. L. Streator,
and Mr. R. L. Taylor who not only opened schools in Yorkshire and
Kansas, but provided essential and timely aid and encouragement. For
help in selecting the books analyzed in the study, the authors are indebted
to Ruth Gagliardo, Director of Library Services, Kansas State Teachers
Association; to Mildred L. Batchelder, Executive Secretary, American Li-
brary Association of Libraries for Children and Young People; to F. Phyllis
Parrott, Children's Librarian, Reading, Berkshire; and to Joan Butler,
Herfordshire County Library. Hermina Nichols rendered important as-
sistance in rating the data from the books.

PAUL V. GUMP, PHIL SCHOGGEN, and FRITZ REDL (Chapter 9). Sincere
appreciation is extended to the personnel of University Boys' Camp, and
to Maxine Schoggen, Ted Goldberg, and Brian Sutton-Smith who served as
observers.

NEHEMIAH JORDAN (Chapter 10). The help and co-operation of Dr.
Fritz Redl, Dr. Harold L. Raush, and Mrs. Florence W. Glaser were es-
sential for the completion of this investigation.

JAMES E. SIMPSON (Chapter 11). Encouragement and help were re-
ceived from Dr. Anthony J. Smith, Dr. Riley W. Gardner, Dr. Gardner
Murphy, and Dr. Mary E. Simpson.

WILLIAM F. SOSKIN and VERA P. JOHN (Chapter 12). The authors are
deeply indebted to Mr. Paul Doty of Bell Telephone Laboratories, who
was a graduate student at the time of this study, not only for his remarkable
achievement in designing and constructing the apparatus used, but also for

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