MODERN BIOLOGY 599 



V. 



4. Animal Psychology 



Animal psychology would rightly have been made part of experimental 

 biology if it had consistently remained on the basis of empirical research. 

 This, however, has been far from being the case; on the contrary, ideas 

 about the psychic life of the animals have varied infinitely up to the pres- 

 ent day, from the standpoint of primitive man, who ascribes to the animals 

 an intelligence of the same kind as his own, to Descartes's conception of 

 animals as completely automatically operating mechanisms. The reason for 

 this confusion is, of course, to be sought in the vague ideas of human psy- 

 chology, which have varied according to the general point of view taken 

 by the different schools of philosophy. It was not until the middle of last 

 century that an exact psychological research began to appear, thanks to 

 precursors like Theodor Fechner, Wilhelm Wundt, and their pupils. This 

 empirical psychology treats of psychical phenomena just like any other ma- 

 terial for observation; it is, as Hoffding says, "no more bound to begin with 

 an explanation of what the soul is than physics is bound to begin with an 

 explanation of what matter is." Unfortunately, those biologists who have 

 dealt with the phenomena of animal psychology have by no means always 

 taken this warning to heart; not infrequently they have followed Haeckel's 

 bad habit of involving themselves in speculations upon the soul as such 

 without having the qualifications to give critical treatment to this com- 

 plicated problem. 



Self-observation the joiindation of psychology 

 The foundation of all empirical psychology is self-observation; on this point 

 an animal psychologist of the old school, such as Romanes, is in agreement 

 with a modern experimental psychologist of the type of Alfred Lehmann 

 (1858-19x1), a pupil of Wundt, professor at Copenhagen. Lehmann main- 

 tains that it is only in one's own consciousness that one can observe psychical 

 states and functional manifestations; the assumption of psychical phenomena 

 in other creatures depends on whether these latter are seen to act in given 

 circumstances as man would do in the same circumstances. As regards one's 

 fellow human beings, this conclusion can be confirmed by means of language, 

 but such a mode of control is wanting in animals; as far as the vertebrate 

 animals are concerned a good deal can be concluded from their bodily struc- 

 ture where it agrees with that of man, but even this check is lacking in the 

 invertebrates. As a general principle of animal psychology there remains, 

 then, according to Lehmann, the principle of ascertaining by experiment 

 whether the animal can adapt itself to new and unexpected situations; 

 whether it can by learning from experience modify its actions to suit the 

 conditions. If this is done, then we have the right to assume the existence 

 of an individual psychic life in the animal — to assume life-phenomena of 



