NO. 6 



EAR EXOSTOSES HRDLICKA 



29 



these abnormalities is larger. In other words, in general, the indi- 

 viduals or skulls that are more subject to ear exostoses will show not 

 only absolutely but also relatively a larger proportion of ears involved 

 than the groups where the growths are less common. Were some of 

 our smaller series as large as are others, the figures would probably 

 be more regular and even more convincing. The meaning of the phe- 

 nomenon can only be that there must exist something like an oto- 

 exostotic " inclination ", which differs in quantity in different racial, 

 geographical, or other groups ; and that the larger the quantity of 

 this X in a group, not only the more individuals, but also the larger 

 percentage of individual ears, will become subject to the growths. 

 The affection acts thus as an entity — perhaps more accurately a " dia- 

 thesis "," a conception which will be found further strengthened when 

 we come to consider the numbers, masses, and character of the ab- 

 normalities under discussion. 



Relative Proportion of Skulls and Ears Affected by Ear Exostoses in the 

 Different Groups 



Group 



(in order of frequency 



of ear exostoses) 



Percentage 



of ears 



affected vs. 



percentage 



of skulls 



Egyptian 



American: 



Eskimo 



Old Pueblo 



N. Dakota 



Florida 



California 



NE. States 



Peru. 



Virginia 



Louisiana 



Arkansas 



S. Dakota, all . . . . 



S. Dakota, Mowbridge 

 Kentucky 



Polynesian : 



New Zealand 



Hawaii 



66.3 



(100) 



87.2 

 76.9 



SIDE 



Since the early history of ear exostoses, it has been known that 

 such growths have a tendency to occur bilaterally, but opinions differed 

 as to the frequency of such an occurrence. 



" In the sense of " a constitutional predisposition or aptitude for some particu- 

 lar development" (Webster's New Int. Diet.). 



3 



