264 
MR. CHARLES S. TOMES ON THE 
Of the dentine-germs or papillae there is little to be said ; they have a well-marked 
odontoblast layer, especially in the eel, and their bases contribute nothing to the for- 
mation of a special capsule. In fact the tooth-germs are only bounded by adventitious 
capsules, due to the condensation of the loose connective tissue around them. The 
enamel-organs long retain a connexion with the oral epithelium, Avhich, however, 
becomes lost after a time, as by the elongation of the tooth its summit soon passes upwards 
into the substance of the oral epithelium ; the “ neck of the enamel-organ ” is seen at b in 
figs. 5, 6, 7, 8, and 9. 
The formation of new dental germs is perpetual, each enamel-germ being formed de 
novo , without being derived from any part of the earlier germs. 
So far I can confirm the statements of Prof. Owen, that “ the germs of the new 
teeth are developed, like those of the old, from the free surface of the buccal membrane 
throughout the whole period of succession — a circumstance peculiar to the present 
class.” 
But I cannot agree in the further statement that “ it is very conspicuous in the 
cartilaginous fishes, &c. ; ” for in these the enamel-organ of each new tooth is 
derived from a part of that of its predecessor, in a manner closely analogous to that 
observed by myself in reptiles, and by Kolliker in the formation of the germ of the 
permanent teeth in man. To the manner of attachment of the teeth of the eel I may 
briefly allude, as it is shown in fig. 10, although I have already described it more fully 
elsewhere (Transactions of the Odontological Society, 1874). Each tooth is perched on 
the summit of a hollow bony column, into which its formative pulp extends for a short 
distance. 
This little column of bone, which is specially developed for and renewed again after 
the loss of each tooth, is formed around the base of the tooth-pulp, which contracts 
below the point where dentine ceases to be formed. 
The dentine ends sharply where the bone begins ; not the smallest fusion of the two 
tissues appears to take place ; and if we imagine dentine to be formed in the lower 
portion of the pulp, where it enters the hollow bony support, we should have a sort of 
rudimentary socket formed. This, however, never takes place in the eel : the dentine 
ends in a slightly rounded border at a point altogether above the bone. 
The teeth of the perch, and indeed of many other fishes, are similarly attached ; 
indeed I think the generalization may safely be laid down that in all cases a special 
development of “ bone of attachment ” takes place. 
The tooth of the mackerel (fig. 13) is somewhat differently attached; it is 
developed in a furrow running round the thin edges of the jaws, and when it is com- 
pleted and erupted it becomes attached to the permanent bony walls of that furrow by 
a development of little bony trabeculae which bridge over the interval and so fix it in 
its place. 
The development of the teeth of the mackerel does not in essential respects differ 
from that described in the eel and the perch, save that the situation of the tooth-germ 
is peculiar, as has already been mentioned (fig. 12). 
