NO. 6 EAR EXOSTOSES HRDLICKA 69 



For Ostmann (1894), too, the cause of the tympanic exostoses 

 among the American aborigines is largely connected with the deforma- 

 tions of the skull, through its efifect on the meatus, which sets up ir- 

 ritation that will lead to exostoses, especially when any other tendency 

 toward such formation exists ; with Whitney, he recognizes in the 

 American materials two main causes — " inborn tendency, with head 

 deformation." Goldstein (1898) inclines to a similar opinion; Russell 

 (1900) believes the tendency to bony tumors in the meatus "is in- 

 creased in deformed crania " ; and there are other suggestions of 

 this nature. 



On the other hand Turner, as early as 1879, though he found 

 exostoses in a deformed Peruvian and a flat-head Chinook, states 

 that " there was nothing in the two skulls to indicate that the growths 

 may have been induced by the artificial deformation." For Virchow 

 (1893) head deformation was without effect on the production of 

 these growths ; for Ten Kate (1896) head deformation had " no con- 

 nection with ear tumors " ; and for Von Luschan ( 1896) ear exostoses 

 " cannot be attributed to head deformation." 



It is plain from the above that the influence of artificial skull 

 deformation on the production of ear exostoses is still problematical. 



However, with the observations already on record and the extensive 

 materials that form the basis of this study, it should be possible to 

 throw more definite light on the matter. Let us see how the principal 

 American data on ear exostoses will range themselves in relation to 

 head deformation. 



The lessons of the table on page 70 are not as conclusive as might be 

 desired, yet they are not valueless. The records show that undeformed 

 American Indian skulls may be practically free from ear exostoses, 

 may be involved slightly to moderately, as in the Calif ornians, or 

 may present a very marked involvement, as in the Coahuilas. An 

 absence of cranial deformation is therefore no index of freedom from 

 the growths. 



There appear in the table several other points worthy of notice. 

 The Argentine Calchaqui, though generally afifected by more or less of 

 occipital cradle-board flattening — artificial but very gradual and prob- 

 ably unaided deformation — are. in the available series, free from 

 ear exostoses ; and the Vancouver Islanders, all of whose skulls show 

 the artificial circular or Aymara shaping, which in some cases is 

 known to reach very marked degrees on the island, show the growths 

 relatively but very rarely. On the other hand the Chinooks, all of 

 whose heads are deformed by more or less pronounced fronto-occipital 

 flattening, present a very high proportion of the abnormalities. 



