IT is not the intention to present in this publication the whole of animal psychology in a systematic way, for that would be a task beyond me. Neither is it my purpose to deal exhaustively with some special aspect of animal psychology, such as, for instance, the techniques used in the study of sense-perception or of the instinctive life, for such a task would mean considering the entire literature concerned --and such an obligation I could not meet under the present circumstances. Actually I have aimed at a much more modest goal, namely, the presentation of a few special problems of animal psychology on which I worked with my students, or which I have selected for special treatment in my lectures, all of which contribute directly to comparative psychology.
The experiments to which I shall refer were carried out with limited resources. It is the very simplicity of the apparatus and methods used for these experiments which leads me to hope others, when they read about them, will be encouraged to take a greater practical part in research in animal psychology. Certainly animal psychology can be studied as an independent science, but we for our part were rather concerned with combining problems of animal and human psychology, so as to throw light on each problem from both sides.
I am very much indebted to Professor Julian S. Huxley, who kindly arranged for me to observe animal behaviour in the London Zoological Gardens.
I should like to record my thanks to Dr H. Honigmann for much advice on zoological problems which arose during the writing of this book.
I am particularly grateful to my friends Miss Alice I. Taylor and Mr Herbert S. Jackson for undertaking the tedious and time-consuming task of translating.