spite of its size, however, it seldom causes
interference with breathing or swallowing, and it has comparatively
little effect on the general health. Clinically, the induration and
fixation of the tumour suggest its epitheliomatous character, but the
absence of a primary growth in the mouth or pharynx excludes its being
a metastasis in the lymph glands.

Unless completely removed at an early stage, recurrence inevitably
takes place.

Primary carcinoma may also occur in a supernumerary thyreoid, and in
the para-thyreoid glands.

We have met with a case of _paraffin epithelioma_ on the neck, and a
similar type of epithelioma may be met with in a lupus or a burn of
long standing.

#The Thymus Gland.#--The thymus gland begins to diminish in size
towards the end of the second year, and by the time puberty is reached
it has entirely disappeared. In some cases, however, the process of
involution fails to take place, and the gland may even undergo
hyperplasia and exert pressure on the trachea, the great blood
vessels, or the left vagus nerve and its recurrent branch. The
enlargement of the thymus may be part of a general lymphatic
hyperplasia--known as the _status lymphaticus_.

The pressure effects may be entirely referable to the trachea--_thymus
stenosis of the trachea_--giving rise to progressive dyspnoea
accompanied by stridor, with paroxysmal exacerbations during which the
child becomes asphyxiated. It is only expiration that is interfered
with, as with each inspiratory effort the gland is sucked in towards
the mediastinum and so frees the air-passages, while with expiration
it rises again, and, becoming jammed in the upper opening of the
thorax, exerts pressure on the trachea, and during expiration a soft
swelling is sometimes recognisable in the episternal notch. The
paroxysms occur at irregular intervals, and any one of them may prove
fatal. In some cases the symptoms seem to be associated with pressure
on the blood vessels and nerves rather than on the air-passages, and
in these there is distension of the veins and a tendency to syncopal
attacks.

The only way to afford relief is to expose the gland and withdraw it
from behind the sternum by making traction on its capsule. If the
breathing is not thereby improved, the capsule should be opened and
the gland shelled out.

The term _thymic asthma_ has been applied to another form of disturbed
respiration due to a large thymus, which comes on suddenly in infant