MENTAL AND SOCIAL EVOLUTION 113 



Reflexes and groups of reflexes, called instincts, are 

 hereditary. He calls them hereditary activities. They 

 are so, because the characteristic response to stimula- 

 tion of the nerves producing these activities, is pro- 

 duced by the anatomy of the nervous system. They 

 are in no sense shaped by individual training, only 

 improved. 



Sometime before birth man has as many brain cells 

 as he will ever have. But at that time, they are mere 

 balls ready for unwinding, when excitations from the 

 sense organs are sufficiently intense. These unwind 

 into threads of conduction during life, it is to be 

 presumed, as the "mind" becomes more and more 

 vigorous, intelligent, and its psychic phenomena more 

 automatic. They, perhaps, are not at any time of life 

 all unwound. Thus man never ceases, during life to 

 develop mentally, and in old age, intelligence is still 

 enlarging, because unused cells ever remain, for form- 

 ing new avenues of thought, in his brain. It would 

 seem, that a life time is too short for the develop- 

 ment of so many, just as it would take more than a 

 life time to count them. The somatic cells cease to 

 multiply in later life. So if a piece of the brain is 

 destroyed it does not grow again, but is filled in, with 

 supporting tissue. But as long as we live, the in- 

 numerable nerve cells existing in the brain are capable 

 of throwing out new fibres which connect with other 

 fibres, and thus form new short cut channels for the 

 passage of excitations from sensory points to motor 

 muscles. The short cuts from one ganglia to another 

 enable man to acquire new habits that in time become 

 automatic. They quicken thought, and multiply the 

 avenues for human activity. 



"It is possible, even highly probable, that a special 



