328 'JourtinJ of Comparative Neurology and Psychology. 



Theoretical Views and Gitidixg Principles. 



Perhaps the main characteristic shown throughout v. ITexkull's 

 work is the abhorrence of anything vague, ill-defined or mystical. 

 In his early papers he sets forth clearly the ideal of scientific work as . 

 the discovery and presentation of what is verifiable or demonstrable. 

 ''We have to do only with processes that can be objectivel}' demon- 

 strated, and to write the history of these processes in an animal 

 from the moment of stimulation to the resulting reaction" (9, p. 

 559). This led him at once into a polemic against authors that used 

 psychic explanations in work on animal behavior (see 7, p. G08 ; 9, 

 etc.). The circle was soon widened, and in 1902 v. Uexkiill declares 

 that a war of extermination has arisen between comparative physiol- 

 ogy and comparative psychology, a war that spells annihilation for 

 one of the combatants and "both are determined to carry the fight 

 to the end" (24). His fundamental jwint is, of course, the fact 

 that there is no way of observing or verifying the existence of 

 psychic phenomena in animals, so that they cannot form a part of 

 a strictly verifiable science; and a further postulate is that all ob- 

 jective processes can and should be fully presented and accounted 

 for without bringing in anything from outside. To substitute psy- 

 chological interpretations for certain steps of objective experimental 

 analysis is vicious and destructive of consistent science. V. 

 ITexkiill's polemic j^apers take extreme positions and are written with 

 much picturesqueness of statement; they are of great value for 

 rousing to a realization of the difficulties those who need such a 

 spur. Apparently, however, all the valuable results that would 

 be reached by utterly destroying the unhappy comparative psy- 

 chologists would be equally well attained by keeping carefully sepa- 

 rate the two fields of work. If the experimenter never substitutes a 

 psychological explanation for a physiological one, he may also be 

 interested, as a separate problem, in the development of mind, with- 

 out injury to his objective scientific work. 



This same demand for objective verifiable results, without admix- 

 ture of anything else, has led v. Uexkiill to take a i)art, with Beer, 

 Bethe, and others, in trying to establish a purely objective nomen- 

 clature for the processes occurring in the movements of animals (18; 



