Human Physiology. 291 



diseases may be propagated, and passed on, even in modified 

 forms, to posterity. Gout is, beyond doubt, transmissible, and 

 from its origin is looked upon as an aristocratic disease. It 

 is, however, often fatal, and is allied to apoplexy, the tendency 

 to which is shown in clearly inherited bodily configuration. 

 Weakness of sight, near-sightedness, and other defects of vision, 

 are hereditary, as are blindness, deafness, and similar defi- 

 ciencies ; so of tendency to fatal hemorrhages. Legal autho- 

 rities recognise the hereditary character of various forms of 

 insanity, and they should equally recognise hereditary ten- 

 dencies of an equally strong and ungovernable character to 

 various crimes, especially to those of theft and murder. The 

 tendency to suicide is very decidedly hereditary, arising, per- 

 haps, in the mental condition of the mother at the period of 

 conception, or during pregnancy, and then handed down 

 to posterity. 'Suicide, it is well known, prevails in some 

 families for several generations, as one of several kinds of 

 transmitted manias. 



In men, as among breeds of animals, the prolific character is 

 hereditary in some families, as in others the reverse. There are 

 families in which almost every member for several generations 

 has had from twelve to twenty children. Longevity is equally 

 remarkable as belonging to certain families. In considering 

 the probable length of the life of any person, or even the pro- 

 bability of his recovery from any disease, we wish to know 

 whether his parents and ancestors were long or short-lived 

 people. 



When both parents come of long-lived families, or strong, or 

 prolific, or intellectual, the peculiarity will be intensified in the 

 children. This law provides for the strengthening and increase 

 of all good qualities ; while the like effect is produced by the 

 conjunction of evil influences ; only many of these, being of a 

 destructive character, are naturally self-limiting. 



The effect produced upon the character of the child by 



