282 Philosophy of Botany. 



anatomical structure of the brain, and has been fully attested 

 in the clinical practice as a satisfactory explanation of the 

 cause of intellectual disturbances. It is the immense pre- 

 ponderance of the association centers over all the other cere- 

 bral divisions which secures the intellectual superiority of man 

 over the highest intellig-ences of all other animals, in neither 

 one of which a like relation occurs. Lesions, mechanical or 

 pathological, in the association centers are the source of mental 

 disturbances. Should conducting channels in any other part 

 of the body happen to take place, anaesthesia or paralysis re- 

 sults in the afifected parts, consciousness and intelligence re- 

 inaining intact. Injury to the sensitive spheres produces loss 

 of the respective sensual perceptions of sight, hearing, etc., 

 but disturbances in the associated regions means intellectual 

 aberration. 



In respect to the evolution of the human brain and mind, 

 the lower animals seemingly are at some advantage in achiev- 

 ing so soon after birth the faculty of taking care of themselves, 

 -and perfecting the cerebral integration in an incomparably 

 shorter period than man does. 



This apparent tardiness is, however, nothing more or less 

 than a prolonged plasticity and long-continued receptivity for 

 cell production and extension of association tissue and storage 

 of sense and reflective impressions. 



Other conditions being equal, it is the prevalence of this 

 quality which conditions the differentiation not only between 

 individuals, but also between the races. The dark-colored 

 tribes attain to sexual and intellectual fullness much earlier, 

 greatly to a disadvantage In regard to docility and training. 

 Under this aspect I accept the view of Alexander von Hum- 

 boldt on the differentiation of man: "Mankind presents a 

 graduation into more docile, higher cultivated, through intel- 

 lectual culture more ennobled, but not imconditionally nobler 

 races. All are in the same measure destined to enjoy liberty, 

 which in the more barbarous conditions consists in personal 

 independence and in the civilized state, under the protection 

 of political institutions, secures for all equal rights." Diver- 

 sity of adaptation, conditions of climate accelerate or retard 

 the social progress, but all have to struggle for its achieve- 

 ment under the slow and severe process of social evolution. 



