Jknnings, UexkuU on P/tysiology of Behavior. 317 



Investigations. 

 Von llcxkiill began as a student of the nerve-muscle preparation 

 of the frog (1). He quickly determined to carry the study of the 

 questions involved to the lower animals ; this plan, carried out largely 

 at the ISTaples Station, led to fundamental results. The work first 

 undertaken was a study of the reflexes of the cuttle-fish (3, 3, 4, 7). 

 This was followed by a study of certain sensory problems on the 

 skate (9), by work on the muscle and nerve physiology of the worm 

 Sipunculus (11, 25), and by an extensive series of thorough and 

 fundamental papers on the nerve-muscle and sensory physiology of 

 the sea urchin (10, 12, 13, 15, 16, 19, 20). Through these studies 

 the author had developed the outlines of an original system of nerve- 

 muscle physiology, having at its basis the concept of tonus. This 

 system he developed farther in the series of Studies on Tonus (25, 

 27, 28, 30, 31), — a series dealing with various invertebrates, which 

 is still in progress, and which we hope may count many numbers 

 besides the five that have appeared. Arising in connection with his 

 systematic series of investigations there have come from his pen 

 many incidental contributions, including notes on special points in 

 nerve-muscle physiology (1, 5, 6, 8, 14, lY, 32), studies of rhythm 

 (23, 26), and discussions of fundamental scientific questions (18, 22, 

 24, 33). In 1905 a brief textbook (29) was published, giving an 

 outline of the views to which he had come, with directions for prac- 

 tical work. 



Characteristic of v. Uexkiill is the intellectual working over of 

 results at the time they are reached, so as to give a graphic and com- 

 prehensible scheme of the way processes occur. This appears in 

 the very first studies, on the cuttle-fish (2, 3, 4, 7) ; they show the 

 author's characteristic abhorrence of everything vague, and particu- 

 larly his objection to psychic explanations in physiology. They 

 contain much important detail on the physiology of muscle and 

 nerve. The paper on the skate (9) is largely a polemic against the 

 use of terms implying consciousness in the nerve physiology of lower 

 animals, directed mainly against W. Wagel. The account of the 

 skate is intended to illustrate the purely objective treatment of the 

 facts, and is perhaps not in ifself a sti'ong example of the value of 



