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Transactions of the 
groove of uncovered papillae corresponding in number to the future 
teeth, "the dental papillae;" (iii) the incapsulation of these free 
papillas by the growing up of the sides of the groove, -which finally 
arched over and met above them. I'hree stages were distinguished, 
viz. the papillary stage, the follicular stage, and the eruptive 
stage. 
Professor Huxley some years ago demonstrated that the stage 
of free papillae at no time existed in the frog and the mackerel, 
while more recently Kolliker has traced out the process as it occurs 
in man with great accuracy, and has shown that all the changes 
take place beneath an unbroken surface of epithelium. As respects 
Batrachia and Eeptilia, the accounts given by Professor Owen, 
who gives detailed descriptions in all respects according with the 
theories of Goodsir, are still accepted. According to the researches 
of Mr. Charles S. Tomes, the following facts may be predicated of 
the development of the teeth of Batrachia and Eeptiha. 
There is at no time any primitive dental groove or fissure, but 
the whole process takes place in the midst of solid tissue, and at a 
distance from the surface ; consequently there is no papillary stage, 
nor indeed anything that can fairly be called a papilla. 
At the inner side of the teeth already in position, where Pro- 
fessor Owen describes a dental groove, is an area occupied by forming 
teeth-sacs, but these latter lie beneath an unbroken surface of 
epithelium. From the oral epithelium dips in an inflection, in 
section like a tubular gland ; at the extremity of this, and from it, 
an enamel organ is developed, and a dentine germ appears beneath 
the cap of the enamel organ thus formed. The enamel organs of 
successional teeth are derived from the epithelial necks of their 
predecessors, and the depth to which these processes of epithelium 
penetrate is often great. The enamel organs have no stellate 
tissue, but consist mainly of the enamel cells with the reflected 
layer or external epithelium of the enamel organ feebly expressed. 
The teeth of Ophidia consist of dentine and enamel, and have 
no cement, as is stated by Professor Owen : that the outer layer is 
enamel is conclusively proved by its development. Enamel organs 
are derived from an inflection of the oral epithelium, as in Lizards 
and Batrachia. Some peculiarities having relation to the great 
extensibility of a smaller mouth however exist. Thus the inflection 
of epithelium is tortuous, and the whole series of tooth-sacs are 
enclosed in an adventitious connective-tissue capsule ; moreover, the 
teeth which have attained some little length become laid down, so 
as to be parallel with the jaw. The teeth of all Eeptilia, which are 
attached by anchylosis, owe their fixation to a special development 
of new bone, removed and formed again with the change of each 
tooth, and not to the ossification of the tooth-capsule, as generally 
supposed. The several views advocated by Mr. Tomes were fully 
