278 Animal Intelligence 



willingness to leave the eggs, showing that the disposition 

 to remain over them is instinctive. If we start with forms 

 of similar sedentary mode of life, it is easy to see that re- 

 maining over the eggs would be the most likely thing to 

 happen, even if no instinctive regard for them existed. 

 The protection afforded would, however, be quite sufficient 

 to insure the development of the instinct, natural selection 

 favoring those individuals which kept their position un- 

 changed long enough for the eggs to hatch." 1 



Professor Whitman proceeds to study the ' Disposition 

 to Resist Enemies ' and the ' Periodicity ' in the same genetic 

 way. 



The most important of all original abilities is the ability 

 to learn. It, like other capacities, has evolved. The 

 animal series shows a development from animals whose 

 connection-system suffers little or no permanent modifica- 

 tion by experience to animals whose connections are in 

 large measure created by use and disuse, satisfaction and 

 discomfort. 



Some of this development can be explained without re- 

 course to differences in mere power to learn, by the fact 

 that the latter animals are given greater stimuli to or re- 

 wards for learning. But part of it is due to differences in 

 sheer ability to learn, that is, in the power of equally 

 satisfying conditions to strengthen or of equally annoying 

 conditions to weaken bonds in the animals' connection- 

 systems. This may be seen from the following simple and 

 partial case: 



Call i and 2 two animals. 



Call C a and C 2 the internal conditions of the two animals 



1 Biological Lectures from the Marine Biological Laboratory of Woods 

 Holl, 1898, p. 323 ff. 



