142 A MANUAL OF DENTAL ANATOMY. 



reptiles (a fact also made out in the newt by Dr. Beale), clearly and 

 strongly expressed the same view as to the origin of the enamel 

 organ, and hence of the enamel. And whilst regretting that their 

 hold upon the minds of anatomists has been so strong as to en- 

 courage deductions therefrom going wider and wider of the mark, I 

 would not be understood to set small value upon the observations 

 of Arnold and Goodsir. They were a step in advance, and were 

 probably as accurate as the methods of investigation then in use 

 would allow of : moreover, the error in observation is very easy to 

 account for, as, the epithelium having peeled off as a result of de- 

 composition, or the use of weak spirit, the state of things left does 

 not widely differ from that described by Goodsir. 



The subject rested for many years without further advances, but 

 in 1863 Professor Kolliker demonstrated, beyond all cavil, the real 

 origin of the enamel organ and its relations to the oral epithelium, 

 the dentine organ, and the dental sac. 



His views, substantially correct, have been elaborated by Wal- 

 deyer, Kollmann, Hertz, Legros and Magitot, Wedl, and others, but 

 only in minor particulars have they been modified. 



The development of the teeth of reptiles was found by a pupil of 

 M. Kolliker's, M. Santi Sirena, to have several features in accord 

 with that of mammalian teeth ; my own researches on the teeth of 

 Batrachia and Fish and Reptiles, elsewhere detailed, have proved a 

 striking general similarity in the process throughout the vertebrate 

 kingdom, though they are not in accord with the views of Pro- 

 fessors Owen and Giebel. 



Dental Follicle. In the foregoing account little mention 

 has been made of the tooth follicle or tissue forming a 

 capsule-like investment around the dentine germ and enamel 

 organ. At an early period of development the tissue form- 

 ing the dentine papilla of a mammalian tooth is seen to be 

 prolonged outwards and upwards from its base (see h in 

 Fig. 64) these processes appear to grow rapidly upwards, 

 so as to embrace the enamel organ; but whether this is 

 really so, or whether it is merely that the ill-defined tissue 

 in which the dentine forming organ has itself originated is 

 in this region also becoming more pronounced, it is hard to 

 say. This up-growth from the base of the dentine papilla 

 is the first appearance of a special dental sacculus, which is 

 thus derived from a source identical with that of the forma- 

 tive organ of the dentine. 



