64 PHILOSOPHICAL NOTES ON BOTANICAL SUBJECTS. 



that the twin in England should have the same idea roused in his 

 brain, by the same associated idea, at the same time ! 



Nevertheless, the twin brains are associated during intra uterine 

 life, almost as much as the cerebral hemispheres of one brain are 

 associated. Moreover, during their childhood, the twins continue 

 to be associated, and must have their ideas continually roused 

 in the same way, and at the same time, so that one brain 

 becomes thoroughly attuned to the movements of the other.* 

 However this may be, it does not seem easy to understand how, 

 when two brains are located in different towns, the same idea can 

 occur synchronously in both of them, unless there be some other 

 means of intercommunication, at present unknown to us. 



In the lower animals, natural selection has occurred through 

 the shaping of other parts of the body aided by an advancement in 

 the complexity and power of the brain. But in man, after natural 

 selection had shaped his other parts up to a certain pitch of 

 suitability, as in other animals, through inheritance, his further 

 advancement had to be done through spontaneous variations of the 

 most important organ — the brain — that regulator and director not 

 only of self, but of others combined in a society. Inheritance was 

 still of the first importance, but it was shifted from the son and 

 daughter to all the members of that society, or at all events to all 

 those who may have been fitted to assimilate and utilize any spon- 

 taneous and useful variations, which occurred in the brains of any 

 of its members. Natural selection continued to exercise its 

 general directive functions for good, with many ups and downs, 

 which did not always seem good. There does not seem to me any 

 necessity to look upon natural selection as having failed in its 

 career, when applied to the mental development of man. 



* There are striking examples of similar urroundings, creating similar 

 thoughts in two distinct brains, and the most striking instance is that of 

 Dan\in and Wallace. This may account for the members of one family or of 

 any small community often having all their minds cast pretty nearly in the 

 same mould. 



