with _gonorrhoeal infection_,
and with _rheumatism_, especially that following scarlet fever, and are
apt to be persistent or to relapse after apparent cure. In the _gouty_
form, urate of soda is deposited in the wall of the bursa, and may
result in the formation of chalky tumours, sometimes of considerable
size (Fig. 114).

[Illustration: FIG. 114.--Section through Bursa over external malleolus,
showing deposit of urate of soda. (Cf. Fig. 117.)]

_Tuberculous disease_ of bursae closely resembles that of tendon sheaths.
It may occur as an independent affection, or may be associated with
disease in an adjacent bone or joint. It is met with chiefly in the
prepatellar and subdeltoid bursae, or in one of the bursae over the great
trochanter. The clinical features are those of an indolent hydrops, with
or without melon-seed bodies, or of uniform thickening of the wall of
the bursa; the tuberculous granulation tissue may break down into a cold
abscess, and give rise to sinuses. The best treatment is to excise the
affected bursa, or, when this is impracticable, to lay it freely open,
remove the tuberculous tissue with the sharp spoon or knife, and treat
the cavity by the open method.

_Syphilitic disease_ is rarely recognised except in the form of bursal
and peri-bursal gummata in front of the knee-joint.

_New growths_ include the fibroma, the myxoma, the myeloma or
giant-celled tumour, and various forms of sarcoma.

#Diseases of Individual Bursae.#--The _olecranon bursa_ is frequently
the seat of pyogenic infection and of traumatic or trade bursitis, the
latter being known as "miner's" or "student's elbow."

[Illustration: FIG. 115.--Tuberculous Disease of Sub-deltoid Bursa.

(From a photograph lent by Sir George T. Beatson.)]

The _sub-deltoid_ or _sub-acromial bursa_, which usually presents a
single cavity and does not normally communicate with the shoulder-joint,
is indispensable in abduction and rotation of the humerus. When the arm
is abducted, the fixed lower part or floor of the bursa is carried under
the acromion, and the upper part or roof is rolled up in the same
direction, hence tenderness over the inflamed bursa may disappear when
the arm is abducted (Dawbarn's sign). It is liable to traumatic
affections from a fall on the shoulder, pressure, or over-use of the
limb. Pain, located commonly at the insertion of the deltoid, is a
constant symptom and is especially annoying at night, the patient being
unabl