CHAPTER XIII 



ANIMAL BEHAVIOR 



In preceding chapters we have touched upon many aspects of 

 the behavior of animals in their general relation to their sur- 

 roundings, and also under such special conditions as commensal- 

 ism, symbiosis, and parasitism. Since this subject is receiving 

 considerable attention from scientists to-day, we may consider 

 briefly a few further aspects of it here. We shall, in general, 

 note the behavior of the animal as a whole rather than of its 

 various organs and tissues, using the term in a broad sense to 

 indicate responses to the various stimuli which the animal may 

 be subjected to. Behavior may be either conscious or uncon- 

 scious, but, with this use of the term, consciousness is not 

 necessarily implied or excluded ; we shall, however, endeavor to 

 ascertain how far consciousness is present in animal activities. 



An emulsion of oil and water, as seen under the microscope, 

 exhibits streaming movements, and behaves precisely like living 

 protoplasm under similar conditions ; the emulsion is not con- 

 scious of its behavior ; is the protoplasm ? The solution of 

 this problem is difficult. We do not hesitate to explain the 

 behavior of lifeless matter by purely physical or chemical laws, 

 or to admit that it depends on similar laws not yet discovered. 

 But in dealing with living matter we are inclined to attribute 

 to it the same sensations and emotions which we ourselves 

 experience in our complex, conscious behavior, even though 

 there may be much simpler explanations. Thus some scientists 

 have gone so far as to attribute to some of the Protozoa such 

 characteristics as perception, choice, volition, memory, and fear, 

 and the superficial study of the activities of these simple animals 

 might well lead to such a conclusion. 



Let us examine a number of free-swimming Ciliata in a drop 



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