44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 93 



Ballenger (1914, p. 661) attempts, though hardly successfully, to 

 give precise definitions : "An exostosis is a bony tumor growing from 

 the wall of the meatus, and may be either sessile or pedunculated. 

 Hyperostosis is a diffuse thickening of the bony tissue, or a true 

 hyperplasia." 



Ferreri ( 1904) opposes the division into hyperostoses and exostoses 

 as artificial. But Gray (1910. p. 137) accepts Cassell's classification, 

 defining ear exostoses as growths " which are circumscribed and even 

 occasionally pedunculated ; and hyperostoses, in which a general dififuse 

 thickening of the bony walls takes place." 



Manasse (cited by Moller-Holst. 1917. p. 71) says that the hyper- 

 ostoses are broadly based thickenings, the exostoses showing a globular 

 development ; and the same definitions are given by Bauer and Stein 

 ( 1926). For McKenzie ( 1920. p. 457) " osteomata in the meatus may 

 be sessile (hyperostosis) or pedunculated (exostosis)." 



Bauer. Stein. Kaufmann (cited by Alexander) designate the cir- 

 cumscribed protruding bony growths as exostoses, the more diffuse 

 ones as hyperostoses. " Thereby ". says Alexander, " the principal 

 distinction between exostosis and hyperostosis falls ; the difference 

 lies simply in the development. The separation of exostoses and hyper- 

 ostoses of the external auditory canal is not easily possible when they 

 occur at the same time in the same ear passage." Alexander then 

 classifies the growths according to location, into : 



1. Exostoses that proceed from the outer border of the os tympauicum. 



2. Exostoses that proceed from the inner border of the os tympanicum. 



3. Exostoses that arise from the body of the os tympanicum. 



4. The flat but slightly protruding exostoses of the inner part of the canal, 

 coming mostly from the terminal line of the os tympanicum. 



He also classifies the growths pathognomically, of which more later. 



Oetteking ( 1930) separates hyperostoses and exostoses, but says 

 that " there may be transitional forms '", though in shape rather than 

 structure. 



Finally Moller-Holst (1932, p. y;^, loi, 102) expresses himself 

 thus : 



Under hyperostoses Kessel and Ostmann understand general thickenings of 

 the tympanic bone; Kaufmann diffuse bone increase in mass, but also circum- 

 scribed growths ; Hartmann and Virchow flat exostoses ; Manasse broadly 

 based thickenings ; Marx dififuse malformations which are to be counted among 

 the hyperplasias and which originate already in childhood ; Alexander a struc- 

 tural variation, not an abnormality (Missbildung), which when more strongly 

 developed are to be counted with the tumors. Zuckerkandl's exostoses also, are 

 designated by Alexander as hyperostoses. Under exostoses are generally under- 

 stood localized bony outgrowths. 



