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are either pointed, flat, or clubbed, sessile or pedunculated. They fre- 
quently form larger or smaller scales, which cover more or less of the 
pone. They vary from the smallest size visible up to ? inch in length or 
1 inch square. They are often compound, smaller ones growing from 
larger ones as a base. Imbrication is not unusually a marked feature, 
and whether imbricated or not, their direction or ‘“‘trend’”’ almost always 
follows that of the fibres attached at that point. This is very marked 
where adjacent muscles run in different directions, ¢. g. the flexor attach- 
ments of the radius and ulna as contrasted with that of the pronater 
quadratus. (Figs. 11 and 15.) The grooves between the osteophytes 
have sometimes rolling edges, sometimes are as sharp as if cut with a 
knife, and often lie closely together and parallel; they are apparently 
made in many cases by the numerous small vessels. All of the osteo- 
phytes are more or less porous. : 
The color is usually normal, but in some places is of varying shades of 
brown. 
On a section the whole bone is seen to be encased with anew formation 
of bone. This is true not only of the long bones but also of the scapule 
and ossa innominata. Viewing these bones and also many parts of the 
shafts of the long bones on the surface, one would suppose he.had simply 
to do with the original thickened bone which had undergone this porous 
change. But a section shows that there is a complete new formation 
which is added layer after layer around the old bone. These layers (except- 
ing where sclerosis has taken place) are separated by interspaces sometimes 
_ just appreciable to the eye, sometimes a quarter of an inch wide. (Fig.17). 
The outer layer is often very thin, but presents to the eye that deceptive 
appearance of apparent compact tissue which has simply become porous. 
Where sclerosis has taken place or osteophytes are developed, of course 
the thickness of the outer layer is either greatly increased or else unde- 
terminable. The other layers also vary in thickness from the develop- 
ment of the sclerosis from the thinnest possible to one or two lines. 
“These layers may sometimes be traced into continuity with those form- 
ing the healthy portion of the wall’ * of the original bone, especially at the 
extremities of the shaft. (Fig. 4.) At these points, starting from the ori- 
ginal compact tissue, the several layers of the encasing new formation grad- 
ually become more and more widely separated or new layers may appear, 
thus producing a very great thickening at the centre, while at the ends of 
the shaft the thickening gradually (sometimes suddenly) diminishes. The 
interspaces between the layers are sometimes for even an inch wholly 
void, but they are generally filled with intervening trabecule of bone, 
which form a cancellated tissue and also support the superimposed layer 
to which they are always perpendicular. To a very large extent these 
layers have been welded together by sclerosis, and sometimes the new 
growth and the origirial bone present no line of demarcation by which 
they can be distinguished. Where this solidification has taken place, the 
cut surface instead of the uniform ivory-like solidity of normal compact 
* Paget. Surg. Path. F 
Ed. 1863, p. 301-2, and fig. 40. 
