642 THi: POPULAR SCIUJ^CA' MONTHLY. 



bine these impressions and evolve new combinations of them, 

 which are rendered manifest externally by impulses sent through 

 a set of outgoing fibers to the various organs of motion. 



A diagram is here reproduced showing the localized areas of 

 sight, hearing, touch, etc., in the human brain, and their relation 

 to the motor centers. It should be stated, in passing, that these 

 centers are in duplicate, or pairs one of each on each side of the 

 brain. 



The purpose of this article is to show by numerous facts that, 

 when one of the senses is lost by accident, or when it is congeni- 

 tally absent, the other senses, in persons otherwise normally con- 

 stituted, become preternaturally keen, and this in a way to com- 

 pensate in some degree for the loss of power in the disabled or 

 absent sense. It is this that I have ventured to call the " Mutual 

 Aid Society of the Senses." 



The historian William H. Prescott, of Boston, who was him- 

 self blind, used to say that " the blind man saw little outside of 

 the circle drawn by his extended arms, but that within that cir- 

 cle he saw more than those whose eyes were sound." 



In considering my subject I will first narrate a very curious 

 illustration of the strangely wayward, atavistic recurrence of 

 blindness, deafness, and idiocy in collateral branches of an origi- 

 nally tainted stock. 



I am indebted to Dr. A. Graham Bell for a very interesting 

 story about a little hamlet in a certain isolated portion of New 

 England. He happened accidentally at one time to come across 

 a gentleman resident in that section who had an immense mass 

 of genealogical statistics (made out on little slips of paper which 

 he kept stufi:ed in different small bags) covering the family trees 

 not only of his own neighbors, but also of descendants of the old 

 stock now scattered all over New England. 



From this unique material, which Dr. Bell has helped to put 

 in usable shape, he became acquainted with the fact that this 

 hamlet was a very peculiar little town, and had been so for twelve 

 generations ever since its original settlement. Its peculiarity 

 consisted in the fact that one out of every twenty-five of its in- 

 habitants was deaf. Two of the family who were its original 

 settlers had been deaf ; and this original leaven of affliction, like 

 the veritable yeast plant itself, had gone on budding and sprout- 

 ing and ramifying, until at the present day the whole town has a 

 flavor of affliction ; and, strange as it may seem, it is not only deaf- 

 ness (and dumbness) from which its quaint inhabitants suffer: 

 some of them are blind, and some are idiotic. Dr. Bell has so 

 many data in his possession that he has not had time as yet to 

 thoroughly digest them all, but they strike him somewhat in this 

 wise. All the way down and through one branch of an originally 



