CHAPTER IV 

 THE BEHAVIOR OF PROTOZOA 



" One of the first lessons which the study of animal behaviour, in 

 its organic aspect, should impress upon our minds is, that living cells 

 may react to stimuli in a manner which we perceive to be subservi- 

 ent to a biological end, and yet react without conscious purpose 

 that is automatically." C. LLOYD MORGAN, Animal Behaviour. 



The student of the evolution of mind naturally looks with 

 interest to the behavior of those organisms which He nearest 

 to the root of the tree of life. What mental powers are 

 evinced by the lowest animals, or whether, indeed, the lowest 

 animals exhibit any mental powers at all are questions of 

 fundamental importance to comparative psychology. Never- 

 theless with all the theoretic interest and importance attach- 

 ing to the study of the powers and performances of these 

 low forms it is somewhat surprising that until quite recently 

 the subject attracted few serious investigators. 



Binet in his book on the Psychic Life of Micro-organisms 

 . makes one of the first thorough-going attempts to estimate 

 the extent of the protozoan mind. Among the psychic 

 operations which he claims are manifested are : 



1. "Perception of the external object; 



2. "The choice made between a number of objects; 



3. "The perception of their position in space; 



4. " Movements calculated, either to approach the body 

 and seize it, or to flee from it." 



Choice is manifested according to Binet in the selection of 

 food. Many species live on a few kinds of food and refuse 

 others. This choice cannot be explained as due to physical 



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