514 KAYIMOND PEAllL. 



the sumo subject^ and furthermore on account of lack of 

 opportunity. As a result of some incidental observations 

 made during- the course of this work, it lias appeared that it 

 would be profitable to extend the Avork of Parker and 

 Burnett, and this, together with a study of the thermotaxis, I 

 hope to be able to do iu the future. Another field for further 

 work is afforded iu the study of the reactions of regenerating 

 individuals. As this subject did not fall immediately into 

 the general plan of this work, but comparatively little atten- 

 tion has been g'iven to it, yet the work done gives much 

 promise of important results to be gained by more extended 

 investigations. 



So far as possible the details of the movements and 

 reactions will be described fully. It is not easy to see why 

 thei-e is not as much need for a complete knowledge of 

 details in physiological work as in morphological, yet in 

 much of the recent work in comparative physiology only the 

 most general results are reported. To gain a knowledge of 

 the details one must do the work over again. While such 

 more or less general papers are easy to read, and put the main 

 results in such a form as to be easily accessible, yet it is 

 believed by the writer that the solid foundations of com- 

 parative physiology and psychology must consist of detailed 

 " fine " work, just as has been the case in morphology. It 

 seems to the writer that the tendency to abandon the detailed 

 descriptive method in favour of the extreme experimental 

 method iu biological work is unfortunate. Both ways of 

 working are methods of getting at the truth, and, as proven 

 by their results, both are good methods. The current notion 

 of the sufliciency of the experimental method to the exclusion 

 of others is not only an evident exaggeration oi the facts in 

 the case, but, in the opinion of the writer, the exclusive use 

 of the " crucial-experiment " method in work upon the move- 

 ments and reactions of organisms has in some cases hindered 

 rather than hel[)ed us to gain a clear understanding of the 

 ])henomena. The importance of close observational work in 

 the study of animal behaviour has been strongly emphasised 



