202 MATURE STUDIES. 



EXAMPLES OF ANIMAL INTELLIGENCE. 



As the preceding article passed through Knowledge, 

 many interesting letters were received. The following 

 are selected from among these : 



It is a common delusion, founded upon imperfect 

 information, that animals guided by instinct do not 

 modify their proceedings by reason, but persevere in 

 a mechanical repetition of the same acts. Probably 

 no creature with a complex nervous system that was 

 observed with sufficient attention, under a variety of 

 conditions, would be found so deficient in intelligence 

 as this theory imagines. At any rate, it completely 

 breaks down when applied to our common birds, and 

 quite fails to explain the kind of facts to be narrated 

 concerning the house martin. A cottage of many 

 gables, situated on the slope of a wide heath, was for 

 many years the favourite resort of this sociable bird, 

 and in one season as many as thirteen nests were 

 established. Now, according to the instinct theory, 

 they ought to have been all alike, but in eleven cases 

 there were obvious differences, some slight in appear- 

 ance, but probably all-important for the stability of 

 the erection or the comfort of its inhabitants. The 

 simplest nest was quite open at the top, sheltered by 

 projecting eaves, and very roughly finished at the 

 margin. Another variety was built quite up to the 

 woodwork, and had a side entrance left in the rough. 



