NO. 6 EAR EXOSTOSES HRDLICKA 55 



As early as 1878, Schwartze reports that he had oljserved hereditary 

 connections, and Delstanche regards " hereditary predisposition " as 

 among " the best determined causes " of the bony growths in the 

 meatus. 



According to Blake (1880, p. 88) : 



there is one other possible influence which may have a bearing upon the 

 occurrence of these growths, and which is at least worthy of consideration in 

 any future investigations which may be made, and that is, hereditary tendency. 

 Of the more marked cases — that is, cases exhibiting excessive growth without 

 evidence of other aural lesion — I have found, in aural practice, that the majority 

 have occurred in certain families, in the male members of successive generations, 

 the most marked instance being in the three successive generations of one 

 family. 



Masini (1882) found positive evidence of heredity of ear exostoses 

 in one case, and similarly did Boyer, Kirchner, Politzer, and Moore. 

 Kessel (1889, p. 288) states that he can confirm the heredity of the 

 growths out of his own clinical experience. There exists here, he 

 says " a constitution-anomaly which leads to certain disturbances in 

 the genesis of the skeleton, without the possibility of a conclusion as 

 yet as to just what this anomaly consists of." 



Braunberger (1896) affirms that in individual cases heredity is as- 

 certainable. Hartmann (1897, p. 43) has not only seen evidences of 

 heredity of ear exostoses in his own practice, but a review of the litera- 

 ture *on the subject has shown him " the frequent occurrence of 

 hereditary influence in similar cases"; Korner (1904, p. 102) says, 

 " There exists nevertheless in not a few families an hereditary dis- 

 position to these bony new growths " ; and in Bezold and Siebenmann 

 (1908, p. 102) we read, "This anomaly is often found in several 

 members of the same family." 



Gray (1910) states that: " The single constant factor is the innate 

 tendency to the disease and the fact that hereditary influences are evi- 

 dent in many cases is strongly in support of this view." For Ballenger 

 (1914, p. 662), " there are some cases in which heredity seems to be 

 a factor in the production of these growths, as the same condition may 

 be traced through a few generations." O. G. Kessel (1924) declares 

 heredity alone to be the effective cause of the growths, other factors 

 being of but secondary importance. Burton ( 1927), as already noted, 

 calls the growths '* atavisms ", which implies inheritance, and asserts 

 that heredity is among the best substantiated of the causes of the- 

 abnormalities. For Alexander (1930), ear exostoses are "often 

 hereditary ". 



