esser amount. The myeloma is also to be diagnosed from
chondroma, from sarcoma, and from osteomyelitis fibrosa cystica.

[Illustration: FIG. 145.--Radiogram of Myeloma of Humerus.

(Mr. J. W. Struthers' case.)]

_Treatment._--In early cases the cortex is opened up to give free access
to the tumour tissue, which is scraped out with the spoon. Bloodgood
advises the use of Esmarch's tourniquet, and that the curetting be
followed by painting with pure carbolic acid and then rinsing with
alcohol; a rod of bone is inserted to fill the gap. In advanced cases
the segment of bone is resected and a portion of the tibia or fibula
from the other limb inserted into the gap; a tube of radium should also
be introduced.

The coexistence of diffuse myelomatosis of the skeleton and albumosuria
(Bence-Jones) is referred to on p. 474. Myeloma occurs in the jaws,
taking origin in the marrow or from the periosteum of the alveolar
process, and is described elsewhere.

#Sarcoma# and #endothelioma# are the commonest tumours of bone, and
present wide variations in structure and in clinical features.
Structurally, two main groups may be differentiated: (1) the soft,
rapidly growing cellular tumours, and (2) those containing fully formed
fibrous tissue, cartilage, or bone.

(1) The _soft cellular tumours_ are composed mainly of spindle or round
cells; they grow from the marrow of the spongy ends or from the
periosteum of the long bones, the diploe of the skull, the pelvis,
vertebrae, and jaws. As they grow they may cause little alteration in the
contour of the bone, but they eat away its framework and replace it, so
that the continuity of the bone is maintained only by tumour tissue, and
pathological fracture is a frequent result. The small round-celled
sarcomas are among the most malignant tumours of bone, growing with
great rapidity, and at an early stage giving rise to secondary growths.

(2) The second group includes the _fibro-_, _osteo-_, and
_chondro-sarcomas_, and combinations of these; in all of them fully
formed tissues or attempts at fully formed tissues predominate over the
cellular elements. They grow chiefly from the deeper layer of the
periosteum, and at first form a projection on the surface, but later
tend to surround the bone (Fig. 150), and to invade its interior,
filling up the marrow spaces with a white, bone-like substance; in the
flat bones of the skull they may traverse the diploe and erupt on the
inner table. The t