21G S. O. MAST 



tion, but also different positions of the body axis. As soon 

 therefore as a position is reached in which the disturbance 

 causing the reaction no longer exists, the reaction of course 

 stops; the animal therefore retains this axial position." 



I am unable to understand how my critic could have read 

 this statement and the account I have given of orientation by 

 the trial method in fly larvae and various other forms and still 

 maintain that " symmetrical stimulation " and " retention of 

 impressions " is necessary to account for the process observed 

 and described. 



7. Professor Parker implies that there is serious confusion 

 in the sequence of authors' names throughout the entire volume. 

 He writes, p. 463: " It is difficult to understand the ground for 

 the sequence of authors' names such as occurs in the categorical 

 statement made on pages 265 and 266, where, contrary to the 

 common practice, the order of dates is not followed. This loose- 

 ness at times comes to be really misleading where, for instance on 

 page 52, Verworn precedes Loeb with dates 1886 and 1887, while 

 in the bibliography Loeb's earliest reference is given with the 

 date 1888, and Verworn 's with that of 1889." The looseness 

 referred to in this statement is more imaginary than real as 

 any one interested can ascertain for himself. As a matter of 

 fact the criticism would not call for a reply if it did not bring up 

 the question of priority between Loeb and Verworn. 



The sentence containing the dates to which Parker refers in 

 this connection reads as follows : " The study of animal behavior 

 from the physico-chemical point of view was first taken up by 

 Verworn and Loeb in 1886 and 1887." The dates found here 

 clearly have nothing to do with dates of publications recorded 

 in the bibliography, and I can see no reason why they should 

 be misleading, especially since, in referring to the investigations 

 of Verworn on the activities of protozoa, I stated, p. 6, that 

 " these were taken up in 1886, two years before Loeb's first 

 preliminary note on the reactions of animals appeared." I did 

 not go into the matter further because I was not primarily inter- 

 ested in the question of priority concerning the authors in ques- 

 tion. In all probability each of them began work on animal 

 behavior from a purely objective point of view independent of 

 the other. The facts concerning this matter are as follows. In 

 1889 Verworn published a paper entitled Psycho-physiologische 



