I/O Journal of Comparative Neurology and Psychology. 



theory, and contributed vastly to our knowledge of the behavior of 

 lower organisms. 



Fifth Paper. Physiological States as Determining Factors in the 

 Behavior of Lower Organisms. 



In unicellular organisms as in multicellular the forms of reaction 

 to stimuli exhibited clearly indicate the importance of internal factors 

 (physiological states) as determining conditions. "To the same stimuli, 

 under the same external conditions, the same individuals react at 

 different times in radically different ways, (thus) showing the existence 

 of different physiological states of the organism, which determine the 

 nature of the reactions," p. 126. Jennings adduces numerous obser- 

 vations of the behavior of various unicellular organisms and flatworms 

 in proof of the falsity of the prevalent notion that the reactions of 

 these animals are determined almost wholly by external conditions. 

 As a matter of fact all organisms, so far as reactions are concerned, 

 are influenced by both external and internal conditions, and it is only 

 because of the apparent invariableness of the reactions of the lower 

 animals that they are so commonly spoken of as automata which are 

 at the mercy of their surroundings in a quite different way than are 

 the higher animals. 



The paper serves the good purpose of calling attention to the fact 

 that reactions are more often determined by the total state of the 

 organism than by the local action of a stimulus. 



Sixth Paper. The Movements and Reactions of Amceba. 



This paper, like the earlier ones of the volume, rudely shakes the 

 foundations of certain current theories of reaction, and it totally destroys 

 certain explanations of the reactions of simple organisms which have 

 been pretty generally accepted by physiologists. Unfortunately for 

 the peace of mind of certain of the earlier investigators of the move- 

 ments and reactions of Amoeba, the author was not satisfied to accept 

 what had already been done in this field of research as the basis of his 

 work. He chose instead to begin at the beginning and to attempt to 

 verify the descriptions already given. 



Rhumbler and Butschli state that in the normal locomotion of 

 Amoeba there is a forward moving current of endosarc in the middle 

 axis which flows outward at the anterior end of the organism, then 

 backward along the surface. According to these physiologists, the 

 protoplasmic currents within a moving Amoeba are essentially like the 

 movements produced in a drop of water by lowering the surface ten- 

 sion at some point. The axial current moves toward the point of de- 

 creased tension. Consequently Rhumbler and Butschli conclude 



