The method used in this treatise is the result of much thought. After
attempting several other outlines, I have come to the conclusion that
the most graphic representation is that of hypothetical cases for each
lesson—i.e., each chapter represents a typical case, or synthetic
experience. The student may at first glance object to this treatment,
but a short survey will, I hope, convince him that the system is the
only adequate one possible. Note that each experiment is couched in
colloquial terms, the better to carry the atmosphere of the lesson. Of
course the student is expected to vary the program according to his own
requirements: these experiments are to serve merely as outlines. I have
attempted to avoid as far as possible that wealth of technical
terminology so dear to the heart of the average scientific author and so
trying to the beginner: I have dared to hope that my compilation would
be an aid not only to that small band who have dedicated their lives
exclusively to research, but also to the great masses, the dilettantes
and amateurs who might be able to find some inspiration in these pages.
The preparation, both research and field work, has been arduous, but
what accomplishment was ever valuable without some labour and pains? If
my contribution to scientific literature has in some small measure
advanced the penetration of my fellow man and eased his path of loving,
I am amply repaid.
In conclusion, I wish to thank those who have worked with me. Without
their unfailing patience, sympathy and assiduity this little book could
never have been written.
_New York_.
_Thanksgiving, 1929._
E. H.