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VIII. On the Development of the Teeth of the Newt, Frog, Slowworm, and Green Lizard. 
By Charles S. Tomes, M.A. Communicated by John Tomes, F.B.S. 
Received July 23, — Read December 10, 1874. 
The researches of Goodsir, constituting as they did a very material advance in knowledge, 
became so deeply graven upon the minds of scientific men that subsequent investigations, 
tending to modify his conclusions in important particulars, have attracted less attention 
than is their due. 
As long ago as 1853 Professor Huxley (Quart. Journ. Microscop. Science, vol. i.) 
published the statement that, in the frog and mackerel at all events, the tooth-germs 
are at no time in the condition of free papillae ; and in the same paper correctly described 
the connexion existing between the oral epithelium and the enamel-organ in the fully 
formed dental sacs. Thus, although Professor Huxley accepted as in most particulars 
accurate the account given by Goodsir. of the sequence of events in the formation of 
the human tooth-sac, he in some degree anticipated the discovery made by Professor 
Kolliker some years later (Zeitschrift f. wiss. Zool. 1863), that in several Mammalia 
the tooth-germs never pass through any papillary stage, but are from the first deep 
below the surface. 
These observations have been confirmed and extended by Waldeyer (see his article 
in Stricker’s ‘ Histology,’ Syd. Soc. Translation, p. 481), by Dursy (Entwickelungsge- 
schichte des Kopfes, 1869), and by Legros and Magitot (Journal de 1’Anat. et Phys. Ch. 
Robin, 1873); and it has been established to full demonstration that in mammals 
i. There is never, at any stage, an open groove from the bottom of which papillae 
rise up. 
ii. That the first recognizable change in the vicinity of a forming tooth-germ is a 
dipping down of a process of the oral epithelium, looking, in section transverse to the 
jaw, like a deep simple tubular gland, -which descends into the submucous tissue and 
ultimately forms the enamel-organ. 
iii. That subsequently to the descent of the so-called enamel-germ, the changes in the 
subjacent tissue resulting in the formation of the dentine-papilla take place opposite 
to its end, and not at the surface. 
iv. That the permanent tooth-germs first appear as offshoots from the epithelial process 
concerned in the formation of the deciduous tooth-germ (Kolliker) — the first permanent 
molar being derived from a primary dipping down (like a deciduous tooth), the second 
deriving its enamel-germ from the epithelial neck of the first, and the third from that 
of the second (Legros and Magitot). 
MDCCCLXXV. 2 Q 
