492 STRUCTURE AND DEVELOPMENT OF TEETH, W. WALDEYER. 



and to F. Boll (59) for following out the dental nerves in their 

 further course. In recent times, Tomes (29, 40) has most suc- 

 cessfully worked at the finer points of dental structure, and by 

 demonstrating the dental fibres first opened the way to a cor- 

 rect interpretation of the nature of the dentine ; previously to 

 him, as by J. Miiller (16) and Lessing (28), the dental canali- 

 culi were regarded in reference to their contents precisely in 

 the same light as the lacunae of bone. Tomes also furnished 

 numerous and valuable contributions to the comparative ana- 

 tomy of the teeth. On the latter subject, however, the im- 

 portant work of Owen (25) constitutes the principal authority, 

 but those of Erdl, Hannover, Huxley (37), Agassiz (15), F. 

 Miiller, and Henle (20) may also be enumerated. Amongst the 

 points in the histology of the teeth still requiring elucidation 

 the structure of the enamel and the final terminations of the 

 dental nerves deserve to be mentioned. If we except the 

 works of Arnold (12) and Goodsir (21) (who however con- 

 sidered that the teeth originate from free papillae at the 

 bottom of an open dental groove) as constituting the first com- 

 prehensive investigations towards the elucidation of the genesis 

 of these structures, those of Marcusen (31), Huxley (37), and 

 Kolliker (47, 58), have proved of the highest value. Marcusen 

 gave the minute details of the primary origin of the teeth 

 quite correctly, and referred the enamel to the oral epithelium, 

 as Huxley also has always maintained ; and Kolliker's accurate 

 investigations have placed the fact beyond doubt. Purkyne and 

 Raschkow had already demonstrated the enamel organ, Schwann 

 (23) the enamel cells and odontoblasts, and Lent (38) and Kolliker 

 (58) the dentinal processes of the latter. The external epithe- 

 lium has likewise been correctly described and explained by 

 Marcusen. All later observers, Nasmyth, Huxley, Natalis, 

 GuiUot (44), Todd and Bowman (35), Robin and Magitot (46), 

 notwithstanding that they described this epithelium with great 

 minuteness, have furnished us with no new information 

 respecting it. Dursy (67) has followed the papillary pro- 

 cesses of the dental sacculus, together with the intervening 

 .depressions of the external epithelium which frequently 

 appear as glandular structures belonging to the latter, as far 

 as the enamel germ, and from thence on to the papillae of 



