designedly rejected by all anatomists until the time of the confirmation
of their exactness and truth by Purkinjé in 1835.
The results of the laborious investigations of this most original
and indefatigable observer were published, as is the custom in many
German Universities, in two inaugural thesises, the one by Fraenkel
entitled “ De penitiori dentium humanorum structura observationes
the other by Raschskow, entitled “ Meletemata circa dentium
evolutionem both of which were defended in the University of
Breslau in the month of October, 1835.
Purkinjé states that the dentine (zahnsubstanz, substantia dentis)
consists, not of superimposed layers, but of fibres arranged in a
homogeneous intermediate^ tissue, parallel with one another, and
perpendicular to the surface of the tooth, running in a somewhat
wavy course from the internal to the external surface ; and he
believed these fibres to be really tubular, because on bringing ink
into contact with them, it was drawn in as if by capillary attraction. (1)
Upon the publication of this discovery it was immediately put
to the test by Professor Midler, by whom the tubular structure of the
ivory was not only confirmed, but the nature and one of the offices
Leeuwenhoek’s Letter to the Royal Society is noticed as follows : “ Les dents sont composées de
très petits tuyaux transparents et étroits, dont six ou sept cents égalent, à peine un poil de la
barbe.” The merit of directing the attention of anatomists to Leeuwenhoek’s discovery of
the structure of dentine is due to Retzius.
(1) Cruorine extravasated during intense inflammation of the pulp, or by an over-distension
of the vessels produced mechanically as in hanging or drowning, would in like manner be
carried, with the plasma, into the dentinal tubes, and occasion red spots in the tooth-substance ;
the bile-stained serum, in the case of jaundice, would equally affect the capillary tissue of the
tooth with its peculiar tinge ; but it does not follow that the tubes which imbibe such coloured
fluids must necessarily be capillary blood-vessels, and these phenomena, therefore, afford no
proof of the vascularity of human dentine.
of the tubes were determined. He observed that the white colour
of a tooth was confined to these tubes, which were imbedded in a
semi-transparent substance, and he found that the whiteness and
opacity of the tubes were removed by acids. On breaking a
thin lamella of a tooth transversely with regard to its fibres, and
examining the edge of the fracture, Müller perceived tubes projecting
here and there from the surfaces; they were white and
opaque, stiff, straight, and apparently not flexible : this appearance
is well represented in the old figure by Leeuwenhoek. If the lamellae
had been previously acted upon by acid, the projecting tubes were
flexible and transparent, and often very long. Hence, Professor
Müller inferred that the tubes have distinct walls, consisting of an
animal tissue; and that, besides containing earthy matter in their
interior, their tissue is, in the natural state, impregnated with
calcareous salts.
Thus, the discovery by microscopical examinations that the
dentine of the teeth in man and various animals was traversed by
minute tubes disposed in a radiated arrangement in lines proceeding
every where perpendicularly from the surface of the cavity containing
the pulp, may be regarded as established, and to be due principally
to the learned and ingenious Purkinje, who, however, was all the
while unconscious that he had been anticipated, as to the main fact,
a long time before, by Leeuwenhoek.
But the tubular structure of ivory is not the only important
fact in dental anatomy, made known in the Breslau Thesises
of 1835. Purkinje also discovered that the distinct layer of
substance, previously known to surround the fang of the simple
teeth of man and many mammalia, contained corpuscles like those