158 HEREDITY 



through the nervous system, which is the great link 

 between the parts of the parent and those of the 

 child. The very act of procreation is essentially 

 nervous. It is characterized by a degree of nervous 

 excitation which is almost without a parallel, and the 

 consequence of which, when of too frequent occurrence, 

 is in the highest degree prejudicial to the general 

 nutrition of the body. 

 The cause It will be Understood that the most excitable part 



of the ^ 



normal of the nervous system is that which is most easily 



hyperaen- 



sibiiity of affected by vibrations generally. When a person has a 

 and ovary, weak spot, let it be the lungs or the stomach, or the 

 kidney, or the facial nerve, anything such as a chill 

 which disturbs the general health acts with double 

 force on the nerves of that particular part, whichever 

 it may be, and causes a greater amount of irritability 

 or vibratory activity than elsewhere. Now, it is very 

 natural to suppose that the excitability of the nerves to 

 the sexual organs should communicate itself in the 

 first place and in the highest degree to those parts of 

 the nervous system which are functionally most 

 closely related to them — that is to say, to the nerves, 

 to the testis, or to the ovary. Thus it happens that 

 these nerves and the centres in the spinal cord on 

 which they depend are under normal conditions also 

 more excitable than other portions of the nervous 

 system. It follows, therefore, that whenever any 

 action takes place in other parts of the nervous 

 system — or, for the matter of that, in the tissues with 

 which it is connected — there is a greater or less 



