ii4 Instinct and Intelligence 



lower classes of vertebrates ; that they are 

 hereditary is shown by the fact that they are 

 manifested by the young of the same orders of 

 beings in all parts of the world. That they 

 depend largely on work performed by the nerve 

 cells of the mid-brain, including its basal 

 ganglia or lower nervous centres, is shown by 

 the fact that after the destruction of this part 

 of the brain, although an animal may continue to 

 live, its instinctive powers are abolished. Prof. 

 Pagano observes, as the result of numerous 

 experiments on adult and new-born animals, 

 that after their basal ganglia had been destroyed 

 their movements of expression distinctly at- 

 tributable to emotional states were abolished. 

 He asserts that the physiological preorganised 

 mechanism of instinctive and emotional re- 

 actions are to be found at birth and in after- 

 life in the basal ganglia. 1 



We may now pass on from the class of fishes 

 to the Amphibians as represented by frogs and 

 lizards. It is evident the sensory organs and 

 brains of many of these animals are of a some- 

 what higher order than those possessed by car- 



1 Archives Italiennes de Biologic, 1906. 



