96 MARRIAGE AND HEREDITY 



ence of new phenomena in nature, and we have 

 reason to believe that many of the so-called lower 

 animals possess powers of perception, in sight, hear- 

 ing, and smell, far in excess of our own, with all the 

 assistance that science gives us. If the causes of 

 insanity are not always to be detected by the eye, 

 the hereditary character of the malady is incontest- 

 able. As Piibot remarks, every work on insanity is a 

 plea for heredity. Insanity may be bred by worry, 

 though whether a perfectly sound brain ever becomes 

 wholly disorganised from that cause is a moot point. 

 More likely the disease is gradually developed in one 

 or two generations before it declares itself. Once 

 developed, its heredity is unquestionable. As to the 

 proportion of hereditary cases of insanity, Maudsley 

 says " the most careful researches agree to fix it as 

 certainly not lower than one-fourth, probably as high 

 as one-half, possibly as high as three-fourths." ^ The 

 variety of the statistics given by various writers 

 arises from a difference in their methods of observa- 

 tion, some excluding and others including cases of 

 indirect transmission. 



Insanity takes many forms. One of the most fre- 

 quent is a tendency to suicide, the hereditary nature 



1 MauJsley's Pathology of Mind. 



