78 



INHERITANCE 



t 



Chap. XIV. 



dance, showing that an nnusnally early or late tendency to the disease 

 is inheritable. 34 In most cases the appearance of any inherited disease' is 

 largely determined by certain critical periods in each person's life as well 

 as by unfavourable conditions. There are many other diseases which 

 are not attached to any particnliar period, but which certainly tend to 

 appear in the child at about the same age at which the parent was first 

 attacked. An array of high authorities, ancient and modern, could b- 

 given in support of this proposition. The illustrious Hunter believed 

 in it; and Piorry 35 cautions the physician to look closely to the child 

 at the period when any grave inheritable disease attacked the parent 

 Dr. Prosper Lucas, 36 after collecting facts from every source, asserts that 

 affections of all kinds, though not related to any particular period of life 

 tend to reappear in the offspring at whatever period of life they first 

 appeared in the progenitor. 



As the subject is important, it may be well to give a few instances, simply 

 as illustrations, not as proof; for proof, recourse must be had to the autho- 

 rities above quoted. Some of the following cases have been selected for 

 the sake of showing that, when a slight departure from the rule occurs 

 the child is affected somewhat earlier in life than the parent. In the 

 family of Le Oompte blindness was inherited during three generations, 

 and no less than thirty-seven children and grandchildren were all affected 

 at about the same age, namely seventeen or eighteen. 37 In another 

 case a father and his four children all became blind at twenty-one years 

 old ; in another, a grandmother grew blind at thirty-five, her daughter at 

 nineteen, and three grandchildren at the ages of thirteen and eleven. 38 _ 

 with deafness, two brothers, their father and paternal grandfather, all 

 became deaf at the age of forty. 39 



Esquirol gives several striking instances of insanity coming on at the 

 same age, as that of a grandfather, father, and son, who all committed 

 suicide near their fiftieth year. Many other cases could be given, as of 

 a whole family who became insane at the age of forty. 40 Other cerebral 

 affections sometimes follow the same rule,— for instance, epilepsy and 

 apoplexy. A woman died of the latter disease when sixty-three years old ; 

 one of her daughters at forty-three, and the other at sixty-seven : the 

 latter had twelve children, who all died from tubercular meningitis. 41 I 

 mention this latter case because it illustrates a frequent occurrence, 

 namely, a change in the precise nature of an inherited disease, though 

 still affecting the same organ. 



So 



34 ? r ' P „ r ?^ per Lucas ' ' H6 ' e ' d ' Nat -'' 1 have not been able to consult), and all 



differ in the details ! but as they agree 



torn. ii. p. 713. 



Maladies 



p. 135. For Hunter, see Harlan's 

 ' Med. Researches,' p. 530. 



36 ' L'Hered. Nat.,' torn. ii. p. 850. 



37 Sedgwick, 'Brit, and For. Med.- 

 Chirurg. Review,' April, 1861, p. 485. 

 I have seen three accounts, all taken 

 from the same original authority (which 



in the main facts, I have ventured to 

 quote this case. 



38 Prosper Lucas, ' Hered. Nat.' torn. 

 i. p. 400. 



39 Sedgwick, idem, July, 1861, p. 202. 



40 Piorry, p. 109; Prosper Lucas, 

 torn. ii. p. 759. 



41 Prosper Lucas, torn. ii. p. 748. 





