52 SMITHSONIAN MISCELLANEOUS COLLECTION'S VOL. 93 



to hyj3€rplasia during the period of development and ossification of 

 the external auditory canal." 



Hartmann (1893; 1896, p. 43) held that ear exostoses "must be 

 cases of anomalies of development, because of the simultaneous ap- 

 pearance on both sides, the limitation of the anomaly to pars tympanica, 

 and the perfectly uniform consistency of the rest of the bone." And 

 further (pp. 45-46) : 



All of these structures are to lie regarded as anomalies of formation, which 

 begin with the development of the external meatus and come to light with the 

 advancing of the pars tympanica 



If I were to offer proof that these alterations were simply anomalies of 

 development and had nothing to do with inflammatory or morbid processes, I 

 should emphasize : the absence of alterations which could possibly be referred 

 to previous inflammation ; the perfectly uniform condition of the bone, which 

 can in no way be distinguished from the neighboring bone, and especially from 

 that of the squamous portion; the limitation of the hyperostosis to the pars tym- 

 panica ; the uniform occurrence on both sides ; the stationary condition of the 

 tumor in adults ; and finally the hereditary influence so often observed. 



Lake (1898) opposes Hartmann's opinions. But J. Gruber (1897, 

 p. 212) believes similarly " that the development of ear exostoses 

 stands in connection with the growth of the tympanic ring and is to 

 be conceived as an excess product of this." And for Politzer (1902, 

 p. 210), in some cases the origin of the growths may be attributed to 

 '* partial hyperplasia during the stages of development and ossifica- 

 tion of the bony auditory meatus." According to his view, " those 

 bilateral osseous neoplasms which develop without symptoms belong 

 to this class, especially if they are located symmetrically in both 

 meatuses and have a corresponding form. They are usually found 

 in the middle and inner sections of the osseous meatus. They are 

 sessile or pedunculated, and seldom attain such a size that they com- 

 pletely fill the auditory canal." 



Ballenger (1914, p. 161), too, subscribes to these opinions. He 

 says : " They may be due to developmental causes, particularly in 

 those cases wherein the middle and the inner section of the osseous 

 meatus on each side is the seat of the growth. When due to faulty 

 development, the growths are usually small." 



Since the above, the " developmental " origin of ear exostoses 

 received noteworthy further support by Burton (1927). To this 

 observer, 



it seems logical to believe that the exciting agent, whatever its form, acts 

 equally upon the entire canal but is responded to only by those points which 

 are especially susceptible to the stimulus. Which are these points? In the vast 



