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®n tbc jfoimation an^ Structure of 

 Deutal lEuamel/' 



Plates XVIIL, XIX, XX, XXL 

 By T. Lkon Williams, D.D.S. Baltimore, L.D.S, R.CS.I. 



ALMOST every anatomist or histologist of note since the 

 time of John Hunter has made some contribution to the 

 subject of this paper. In going over the literature of the 

 theme, one is struck by the wide divergence of opinion expressed 

 — a divergence which is as marked and emphatic to-day as it was 

 forty or fifty years, ago. Broadly speaking, all who have written 

 on the subject may be separated into two groups or schools: those 

 who have taught that the formation of enamel is effected by direct 

 cell-calcification, and those who have claimed that the tissue is 

 produced by a secretion — by the calcification of a cell product. 

 Between 1850 and i860. Professor Carpenter was maintaining 

 the former position, and during the same time the late Professor 

 Huxley wrote several papers antagonising this view, and claiming 

 that enamel could not be produced by any conversion of a cellular 

 structure. Curiously enough, his main contention was correct, 

 although founded upon mistaken premisses. In 1848, the late 

 Sir John Tomes delivered a course of lectures in which he taught 

 that enamel formation is the result of the calcification of the 

 enamel-forming cells. His son, Mr. Charles Tomes, in the last 

 edition of his work on Dental Anatomy, published in 1894, still 

 holds to this opinion ; and these views are also shared by Walde- 

 yer, Wedl, and many others. On the other side, Professor Schafer 

 in England, Professor Spee in Germany, and Dr. Aijdrews and 

 Dr. Sudduth in America, have maintained that the enamel cells or 

 ameloblasts are not directly calcified, but that they are the active 

 agents in producing the material from which enamel is formed. 



It is not my intention to present a summary of the history of 

 the literature of this subject, and I have mentioned the foregoing 

 names merely to show that the most eminent teachers have held, 



* An abstract of a paper read before the Royal Society, December 12th, 

 1895. From The Lancet. We beg to thank the editor for kindly lending the 

 blocks which form the accompanying plates. 



