In this paper the writer proposes to give
an account of the development of the nose, mouth, and
pharynx. The methods of research employed in this
piece of work have been mainly the use of wax plate
reconstructions, while some embryos have been examined by the microscope alone. However, as the number
of human embryos available was very limited, one has
had to fall back on the literature for descriptions
of some of the stages. It has been found necessary
for the sake of clearness to repeat some of the facts
(1) The tongue is developed from three roots, vi+
tuberculum impar, lateral tongue rudiments and copulei
The tuberculum impar is itself mainly derive4
from the first pair of arches, and ultimately forms
triangular area on the dorsum of the tongue in front
of the foramen caecum. The lateral tongue rudiments
grow up from the anterior edges of the first arches
and enclose the tip of the tuberculum impar betweén
them. The tip and sides of the tongue are formed by
the lateral tongue rudiments. The copula is a swell - ong caused by the union of the second arches in the
middle line. It along with the parts of the second
arches immediately lateral to it form the tongue root,
i.e, the portion between the foramen caecum and the
In this way the whole of the tongue in front
of the foramen caecum is derived from the first arch,
while behind the foramen caecum it is derived from the
(2) The epiglottis is developed from the third
arches and the arytenoid tubercles from the fourth
and fifth arches.
('3) The palatal processes, from which most of the
permanent palate develops, are derived partly from the
maxillary processes but also to a large extent directly from the mandibular arch.
(4) The middle ear and. Eustachian tube are level
oiled from the dorsal extensions of the first. and second
visceral pouches. Thus elements of the first, second
and third arches enter into the composition of its walls.
(5) The faucial tonsil is developed from the remains of the second and appears a considerable time
before the pharyngeal tonsil.
(6) Median diverticula in the posterior pharyngeal wall near the mouth of the oesophagus are a common occurrence in the pig and may also occur in the
human embryo. Their position is pretty constant in
the pig, viz. between the third. and fourth visceral
pouches. They are situated in a position in which
malignant disease is very liable to occur and where
the so called. "pressure pouches" are not uncommon.
These facts are sufficient to suggest that there may
be an embryological element in the - causation of the
pharyngo-oesophageal diverticula met with occasionally
in the adult.