The periosteum is thick and vascular, and when detached carries with it plates and spicules of soft porous bone.  The new bone may be so abundant that it forms a thick crust on the surface, and in the flat bones of the skull this may be heaped up in the form of bosses or ridges resembling those ascribed to inherited syphilis.

In the epiphysial cartilages and at the ossifying junctions, all the processes concerned in ossification, excepting the deposition of lime salts, occur to an exaggerated degree.  The cartilage of the epiphysial disc proliferates actively and irregularly, so that it becomes softer, thicker, and wider, and gives rise to a visible swelling, best seen at the lower end of the radius and lower end of the tibia, and at the costo-chondral junctions where the series of beaded swellings is known as the “rickety rosary.”

The ossifying zone is increased in depth; the marrow is abnormally vascular; and the new bone that is formed is imperfectly calcified.  The result is that the bones may never attain their normal length, and they remain stunted throughout life as in rickety dwarfs (Fig. 133), or the shafts may grow unequally and come to deviate from their normal axes as in knock-knee and bow-knee.

[Illustration:  FIG. 133.—­Skeleton of Rickety Dwarf, known as “Bowed Joseph,” leader of the Meal Riots in Edinburgh, who died in 1780.

(Anatomical Museum, University of Edinburgh.)]

These changes are well brought out in skiagrams; instead of the well-defined narrow line which represents the epiphysial cartilage, there is an ill-defined, blurred zone of considerable depth.

In the shafts of the long bones, owing to the excessive absorption of bone, the cortex becomes porous, the spongy bone is rarefied, and the bones readily bend or break under mechanical influences.  When the disease is arrested, a process of repair sets in which often results in the bones becoming denser and heavier than normal.  In the flat bones of the skull, the absorption may result in the entire disappearance of areas of bone, leaving a membrane which dimples like thin cardboard under the pressure of the finger—­a condition known as craniotabes.

Changes in the Skeleton before the Child is able to walk.—­The fontanelles remain open until the end of the second year or longer, and the frontal and parietal eminences are unduly prominent.  There is sometimes hydrocephalus, and the head is characteristically enlarged.  The jaws are altered so that while the upper jaw is contracted into the shape of a #V#, the lower jaw is square instead of rounded in outline, and the teeth do not oppose one another.  In the thorax, the chief feature may be the beading at the costo-chondral junctions, principally of the fifth and sixth ribs or its walls may be contracted, particularly if respiration is interfered with as a result of bronchial catarrh or adenoids.  The contraction may take the form of a vertical groove on each side, or of a horizontal groove at the level of the upper end of the xiphi-sternum; when the sternum and cartilages form a projection in front, the deformity is known as “pigeon-breast.”