opment.

[Illustration: FIG. 54.--Fibro-myoma of Uterus.

(Anatomical Museum, University of Edinburgh.)]

#Glioma.#--A glioma is a tumour composed of neuroglia. It is met with
exclusively in the central nervous system, retina, and optic nerve. It
is a slowly growing, soft, ill-defined tumour, which displaces the
adjacent nerve centres and nerve tracts, and is liable to become the
seat of haemorrhage and thus to give rise to pressure symptoms resembling
apoplexy. The glioma of the retina tends to grow into the vitreous
humour and to perforate the globe. It is usually of the nature of a
glio-sarcoma and is highly malignant.

#Endotheliomas# take origin from the endothelium of lymph vessels and
blood vessels, and serous cavities. They show great variation in type,
partly because of the number of different kinds of endothelium from
which they are derived, and partly because the new connective tissue
which is formed is liable to undergo transformation into other tissues.
They may be soft or hard, solid or cystic, diffuse or circumscribed;
they grow very slowly, and are almost always innocent, although
recurrence has been occasionally observed. Cases of multiple
endotheliomata of the skin have recently been described by Wise.

_Angioma_, _lymphangioma_, and _neuroma_ are described with the disease
of the individual tissues.

MALIGNANT CONNECTIVE-TISSUE TUMOURS--SARCOMA

The term sarcoma is applied to any connective-tissue tumour which
exhibits malignant characters. The essential structural feature is the
predominance of the cellular elements over the intercellular substance
or stroma, in which respect a sarcoma resembles the connective tissue of
the embryo. The typical sarcoma consists chiefly of immature or
embryonic connective tissue. It most frequently originates from fascia,
intermuscular connective tissue, periosteum, bone-marrow, and skin, and
forms a rounded or nodulated tumour which appears to be encapsulated,
but the capsule merely consists of the condensed surrounding tissues,
and usually contains sarcomatous elements. The consistence of the tumour
depends on the nature and amount of the stroma, and on the presence of
degenerative changes. The softer medullary forms are composed almost
exclusively of cells; while the harder forms--such as the fibro-,
chondro-, and osteo-sarcoma--are provided with an abundant stroma and
are relatively poor in cells. Degenerative changes may produce areas of
softening or liq