The anomalies of this class present many varieties, both when the volume of the bone is greater than natural and when it is less.

An increase in the size of the bones occurs in various forms.

1. They may grow to a greater length than natural. In giants this excess prevails in the whole skeleton; but sometimes it is observed only in particular fingers, toes, or limbs; in the latter case, it may be congenital, or may come on after birth, during the period of childhood or youth.

2. The increase may take place in the breadth and thickness of a bone, at the same time that its texture becomes more dense, and its weight greater. This is hypertrophy, hyperostosis; it may extend over the whole of a bone, or be confined to particular parts of it.

3. The enlargement of a bone may be a consequence of expansion of its texture - of dilatation of its Haversian canals, and, in long bones, of the medullary cavities. It is by this change that the enlargement of cavities which are made up of bones, especially of the skull, is effected: it arises from pressure on the bones from within.

4. Enlargement is sometimes occasioned by the development of various kinds of adventitious growths and tumors in bone.

The Volume Of Bones Is Less Than Natural

1. When the whole skeleton or a part of it, as the head, or one or more of the limbs, has failed in attaining its full growth, whether its small size be observable at birth, or be first exhibited at a later period in a dwarfish growth of the body. Congenital dwarfishness is distinguished generally by an arrested development of the extremities in length, which is at once seen on comparing them with the skull and vertebral column; by the striking appearance of thickness which the articular ends of the bones consequently obtain; and by their deformity generally. Although congenital dwarfishness manifests on the whole a seeming alliance with those changes which are produced by rickets in the growth and form of bones, yet it cannot be certainly said to be due to the existence of that disease in the foetus: its pathology is still unsettled.

2. Or else the small size of bones proceeds from atrophy.