ANIMAL INSTINCT AND INTELLIGENCE 



CHAPTER LIX 



GENERAL PRINCIPLES INSTINCT AND INTELLIGENCE 

 IN HIGHER INVERTEBRATES AND VERTEBRATES 



GENERAL PRINCIPLES 



Having briefly surveyed the salient facts regarding the Ner- 

 vous System and Sense-Organs we naturally pass on to the 

 consideration of those higher manifestations of life known as 

 Instinct and Intelligence, which play a very important part in the 

 adjustment of animals to their surroundings. To do anything 

 like full justice to the subject at least half a volume would be 

 required, and it is only possible here to attempt a brief summary 

 of general principles, adding to this a few typical illustrations. 

 Many other examples, however, will be found in other parts of this 

 book. As regards the present section, the writer wishes to ac- 

 knowledge his great indebtedness to the works of Principal Lloyd 

 Morgan, i.e. Habit and Instinct, Animal Life and Intelligence, and 

 Animal Behaviour, to which are referred those readers who wish 

 further information on this branch of zoology. 



Something has already been said about Reflex Actions (see p. 

 9), which are comparatively simple responses to external stimuli. 

 In very lowly animals, such as Animalcules (Protozoa), these, 

 together with equally simple spontaneous actions, are sufficient 

 to meet all the contingencies of existence. So apparently pur- 

 poseful, however, are many of these actions, that some observers 

 are inclined to ascribe mental powers to such forms. Either to 

 prove or to disprove such a view is impossible, for we have no 

 direct knowledge of the mind of any animal save Man, and can 

 only make more or less probable guesses about other forms. We 

 may feel pretty sure, however, that the evolution of the nervous 



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