and most other teeth, offer a very different character, and one
which has led to many approximations and allusions to the true
structure of dentine, in the works of anatomists who have recorded
their own original observations.
Whoever attentively observes a polished section or a fractured
surface of a human tooth may learn, even with the naked eye, that
the silky and iridescent lustre reflected from it in certain directions
is due to the presence of a fine fibrous structure.
Malpighi, in whose works may be detected the germs of many
important anatomical truths that have subsequently been matured
and established, says that the teeth consist of two parts, of which
the internal bony layers ^dentine) seem to be composed of fibrous,
and as it were, tendinous capillaments reticularly interwoven. (1)
Retzius cites many recent authors, as Soemmering, Schreger(2) and
Weber, (3) who mention the silky glistening lustre of the dentine ; and
Frederick Cuvier in the preliminary discourse of his admirable work
the I Dents des Mammifères,’ observes : “ Les dents de l’homme, de
singes, de carnassiers ont un ivoire d’apparence soyeuse, qui semble
formé de fibres,” p. xxvii. These intelligible hints of the true structure
of the dentine, which the foregoing observers received from a
superficial but unprejudiced inspection, failed, however, to incite them
to a closer interrogation of Nature.
One of her more persevering investigators had, nevertheless, long
before obtained a true and definite answer to his more direct inquiries.
Leeuwenhoek, having applied his microscopical observations
(1) “ Duplici excitantur parte, quarum interior ossea lamella fibrosis et quasi tendinosi
capillamentis in naturam implicetis constat.”—Anatome Plantarum, Lugd. Batav. 1687, p. 37.
(2) Isenflamm und Rosenmüllers Beiträgen zur Zergliederungskunst, band i, p. 3, (1800).
(3) See his Edition of “ Hildebrand’s Handbuch der Anatomie,” band i, p. 206.
to the structure of the teeth, discovered that the apparent fibres were
really tubes, and he communicated a brief but succinct account of his
discovery to the Royal Society of London,(1) which was published,
together with a figure of the tubes, in the 140th Number of their
Transactions. This figure of the dentinal tubes, with additional
observations, again appears in the Latin edition of Leeuwenhoek’s
works, published at Leyden in 1730. The dental substance (dentine) of
the human teeth, and of those taken from young hogs is described as
being “ formed of tubuli spreading from the cavity in the centre to
the circumference.” He computed that he saw a hundred and
twenty of the tubuli within the forty-fifth part of an inch. (2)
Leeuwenhoek also shows that he was aware of the peculiar
substance, distinct from the ivory and enamel, and now termed
the cement or crusta petrosa, which enters into the composition of
the teeth of the horse and ox (3) ; a component part of the tooth which
Hunter speaks of as a second kind of bone ; and which was first
accurately and specifically described by Tenon and Blake.
But these microscopical discoveries may be said to have appeared
before their time: the contemporaries of Leeuwenhoek were not
prepared to appreciate them ; besides, they could neither repeat
nor confirm them, for his means of observation were peculiarly his
own : and hence it has happened that, with the exception of the
learned Portal,(4) they have either escaped notice, or have been
(1) Microscopical Observations on the Structure of Teeth and other Bones.—Philos. Trans.
1678, p. 1002.
(2) See Hoole’s Translation of the select works of Leeuwenhoek, 4to. 1798, p. 114.
(3) Parvimolares, quos bos, dum ad hue admodum juvenis sive vitulus, habuerat, undiquaque
alio osse circumducti erant ” Continuatio Epistolarum, 4to. Lugd. Bat. 1689, p. 7.
(4) Histoire de P Anatomie et de la Chirurgie, Paris, 1770, Tom. iii, p. 460, in which