104 Instinct and Intelligence 



of these basal ganglia is all-important, in that 

 a large part of their living substance is formed 

 of inherited nervous matter, which under appro- 

 priate stimuli regulates the behaviour of the 

 lower classes of vertebrates; energy derived 

 from external and internal sources being trans- 

 muted by the elements of these centres into 

 instinctive movements. (See footnote.) The 

 behaviour of these lower classes of animals may 

 therefore be said to depend on the nature of 

 the structural arrangement and motion of the 

 elements forming the nervous matter of their 

 basal ganglia. In some invertebrates, such as 

 the Crustacea (p. 77), nervous structures exist 

 which control the instinctive movements of 

 these animals, and we shall find that similar 

 organs are present in the brains of amphibians, 



corpus striatum is an autonomous centre ; in other words, whatever 

 its function, that function is exercised independently of the 

 cerebral cortex." (Brain: A Journal of Neurology, May, 1914, 

 pp. 477, 482.) He adds, its nerve fibres become myelinated com- 

 paratively early in foetal life ; that phylogenetically it is a" very 

 old structure consisting of the basal part of the fore-brain. Dr. 

 Wilson further observes that in fishes the corpus striatum is 

 comparatively simple in structure, but in function acts as a "minia- 

 ture brain " ; in reptiles and birds there are additions, and in apes 

 and man it consists of a complex organ closely connected with 

 the optic thalamus "and beyond." Prof. Elliot Smith regards the 

 corpus striatum as that part of the original cerebral hemisphere 

 whereby impressions from sensory organs are brought to bear on 

 the. nervous mechanism regulating an animal's movements, or, 

 in other words, its behaviour. 



