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MR. C. S. TOMES ON THE DEVELOPMENT OE THE TEETH 
The error in Goodsir’s observations was not a very radical one, and was probably, at 
that date, almost inevitable, inasmuch as the processes by which more modern investi- 
gators have the advantage of seeing structures in situ were not then discovered : never- 
theless, though the error in fact was not great, the deductions based upon it effect a 
wider divergence from the truth ; and the terms “papillary stage,” “follicular stage,” &c. 
should be abandoned, as inapplicable to the phenomena observed in any teeth whatever 
which have been satisfactorily examined. The development of the simple teeth which 
have no enamel, and that of the teeth of Fish, Batrachia, and Beptilia, has been but 
little investigated, though the very early appearance of the enamel-germ in other Mam- 
malia lends an additional interest to the inquiry. 
I was myself fortunate enough to obtain specimens of foetal armadillos, from which 
I was able to establish that, although not a particle of enamel was formed, the sequence 
of events was identical with that observed in other mammals *, viz. a dipping down of 
epithelium to form an enamel-organ, which differed in minor respects only from that 
found where enamel is really formed (Quart. Journ. Microsc. Science, Jan. 1874). 
The literature relating to the development of the teeth in Batrachia and Reptiles is 
somewhat scanty. 
Professor Owen, in his ‘Anatomy of Vertebrates ’ (vol. i. p. 389), reiterates the state- 
ment contained in his ‘ Odontography,’ where h£ says, “ The teeth of Reptiles are never 
completed at the first or papillary stage ; the pulp sinks into a follicle and becomes 
enclosed by a capsule ; ” while a more detailed description is given of the process as it 
occurs in the frog, to be again referred to. He also states, “ Dentine and cement are 
present in the teeth of all Reptiles.” 
He also draws comparisons between the condition permanently retained in reptiles 
and various transitory stages of human dentition, which are necessarily open to the same 
objections which apply to his descriptions of development, inasmuch as they arise out 
of these latter descriptions. 
Some advances, however, towards a more correct appreciation of the process have 
been made. In the paper of Professor Huxley’s already referred to, it is more than once 
clearly stated that the teeth of the frog do not pass through any papillary stage, but 
from the first are contained in sacs beneath the surface ; and some years later Dr. Lionel 
Beale (Archives of Dentistry, 1864) published some observations upon the common 
newt, in which he found that the whole process of formation of the tooth-sac took place 
beneath the epithelium, which was intimately concerned in its formation. I am unable 
to entirely concur in his description of either the mode of origin or the structure of 
the tooth-sacs ; but I have less hesitation in expressing a difference of opinion from 
* My attention has since been drawn to an observation of Professor Turner’s, who found a structure homo- 
logous with the enamel-organ in a narwhal (Journal of Anat. & Phys. Nov. 1872); this, which I had over- 
looked, is, I believe, the first notice of a functionless enamel-organ ; but unfortunately sections showing its 
structure and relations undisturbed do not appear to have been made, he having other and more important 
points under investigation in this same specimen. 
