460 INitEKITANCE. Chap. XU 



family are frequently affected, often at about the same age, 

 by the same peculiar disease, not known to have previously 

 occurred in the family. He specifies the occurrence of diabetes 

 in three brothers under ten years old ; he also remarks that 

 children of the same family often exhibit, in common infantile 

 diseases, the same peculiar symptoms. My father mentioned 

 to me the case of four brothers who died between the ages of 

 sixty and seventy, in the same highly peculiar comatose state. 

 An instance has already been given of supernumerary digits 

 appearing in four children out of six in a previously unaffected 

 family. Dr. Devay states ^^ that two brothers married two 

 sisters, their first-cousins, none of the four nor any relation 

 being an albino ; but the seven children produced from this 

 double marriage were all perfect albiuoes. Some of these 

 cases, as Mr. Sedgwick ^^ has shown, are probably the result 

 of reversion to a remote ancestor, of whom no record had been 

 preserved ; and all these cases are so far directly connected 

 with inheritance that no doubt the children inherited a 

 similar constitution from their parents, and, from being 

 exposed to nearly similar conditions of life, it is not surpris- 

 ing that they should be affected in the same manner and at 

 the same period of life. 



Most of the facts hitherto given have served to illustrate 

 the force of inheritance, but we must now consider cases 

 grouped as well as the subject allows into classes, showing 

 how feeble, capricious, or deficient the power of inheritance 

 sometimes is. When a new peculiarity first appears, we can 

 never predict whether it will be inherited. If both parents 

 from their birth present the same peculiarity, the probability 

 is strong that it will be transmitted to at least some of their 

 offspring. We have seen that variegation is transmitted 

 much more feebly by seed, taken from a branch which had 

 become variegated through bud- variation, than from plants 

 which were variegated as seedlings. With most plants tlie 

 power of transmission notoriously depends on some innate 



3* «Du Danger des Mari^ges Con- Chirurg. Review,' July, 18G3, pp. 

 sanguins,' 2nd edit., 186-2, p. 103. 183, 189. 



^^ ' british and Foreign Medico- 



