32 PRINCIPLES OF STOCK-BREEDING. 



and three male children of his mother's sisters, had as 

 many of them as himself." J 



The inherited predisposition to any form of dis- 

 ease may be derived from either or both parents, but, 

 in the latter case, it is also likely to be intensified by 

 being made a dominant character. 3 



The hereditary predisposition to disease may not 

 be observed in a particular individual, but its recur- 

 rence in the offspring shows that the defect has been 

 inherited, and likewise transmitted. In such cases 

 the influence of favorable sanitary conditions may 

 have been sufficient to counteract the inherited ten- 

 dency in some degree, or the absence of exciting 

 causes may have prevented its development, with- 

 out interfering with the potency of its transmission 

 to the next generation. The hereditary predispo- 

 sition may thus be suspended for several genera- 

 tions, and then reappear with an intensity that in- 

 dicates the marked persistence of the hereditary 

 taint, even in individuals that seem to be exempt 

 from it. 



The inherited predisposition to disease, in indi- 

 viduals apparently free from it, may often be detected 

 by its repeated occurrence in some collateral branches 

 of the family. This alternation in the development 

 of hereditary disease is observed, not in rare instances 

 only, but so frequently that it seems to be the rule, 



1 " Surgical Pathology," p. 465. 



8 " Cyclopaedia of Anatomy and Physiology," vol. ii., p. 471 ; Car- 

 penter's " Mental Physiology," p. 369 ; London Lancet, quoted in the 

 Pacific Medical and Surgical Journal, February, 1877, p. 408. (For 

 dominant characters see pp. 77 and 78.) 



