46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 93 



except perhaps for the rare osteomata of the roof, it is merely a con- 

 ventional and convenient suhclivision, without substantial anatomical 

 or pathological foundation. 



STRUCTURE 



A number of authors who dealt with ear exostoses report the re- 

 sults of a histological examination of these growths. The results show 

 difif erences ; some are more or less cancellous and some are compact 

 tumors, but between the two there is no line of demarcation — they 

 connect by intermediary grades. Thus histology, too, fails to afford 

 any definite basis for the differentiation of these neoplasms into dis- 

 tinct categories. About all that can legitimately be said is that the 

 small, pearllike and the smooth, rounded exostoses are generally the 

 more compact, the tumefactions and the large masses prevalently the 

 more cancellous. 



The structure of ear exostoses received attention from the very 

 first report of these cases, that of Autenrieth (1809). The growth 

 was " formed of areolar bone tissue." 



Contrary to this, in Toynbee's experience the tumors were compact. 

 In his Textbook ( i860) we read : 



As far as my opportunities have permitted examination, these tumours .... 

 appear to consist of extremely hard and dense bone. In one case, where a por- 

 tion of the bone was denuded of membrane, it appeared shiny, white and polished, 

 like ivory. In another, where, under the misapprehension of the body being a 

 polyp, caustic had been applied, the bone was exposed and found to be extremely 

 hard and devoid of sensibility. In a third instance, where I observed the mem- 

 brane to be absent, there was a thin layer of cartilage on the surface, beneath 

 which the bone was very hard. 



Delstanche (1878) distinguishes "cellular" and " eburnated " 

 structure of ear exostoses. He says (p. 8) : " Thus some — the cellu- 

 lar exostoses — are formed by areolar bony tissue which is enveloped 

 by a thin layer of compact bone; others — the eburnated exostoses — 

 are completely formed by compact tissue of much density." Schwartze 

 (q. by Delstanche) " is of the opinion that the spongy and compact 

 states of the exostoses represent merely different phases of the devel- 

 opment of the neoplasms, and that exostoses that were at first can- 

 cellous can pass into the state of eburnation ; and he believes also in 

 the possibility of their transformation in the reverse sense. This 

 opinion is also partaken of by Virchow and Nelaton." 



Individual cases were studied histologically by Hedinger, Cocks, 

 Kuhn, Eulenstein, and others. The reports are sometimes rather in- 

 volved, but all agree on one hand in the complete absence of anything 



