At the first point of ossification in a broad bone, we perceive at first reddish spots, then we observe the phosphate of lime spreading in rays from the centre to the circumference of the bone. The osseous rays are very evident upon the bones of the cranium. Portions not ossified at first fill their interstices, which new rays afterwards occupy. All terminate in an unequal manner, without touching, so that by separating an ossified portion of a broad bone from the membranous portion to which it belongs, its circumference looks cut like the extremity of a comb; hence, as we shall see, the origin of sutures. The delicacy of these bones is extreme in the early periods; they have not then any of the texture of the cells. At birth but few of the osseous centres are yet united; cartilaginous and membranous spaces separate them; these spaces are greater towards the angles than towards the edges, and generally at points the most distant from the primitive osseous centres. The bones with many points of ossification are formed of separate pieces, more or less distant from each other. Those with one point only, have but one piece. After birth these bones extend more and more, their thickness and hardness increase; they are divided into two compact layers, the space between which is filled by the texture of the cells; gradually they touch at their edges, and then the sutures are formed in the cranium; for there is this difference between their ossification and that of the long bones, that it takes place always from the centre to the circumference, and that new osseous points are not developed at the circumference to meet those of the centre. But when this happens, the union does not then take place as in the long bones, but sutures are formed; and it is this which occasions the ossa wormiana, which are so much the larger as the osseous point is the sooner developed, because it has had time to extend itself more, before meeting the general ossification of the bone. When a broad bone is developed by many points and there exists upon its surface an articular surface, it is usually the centre in which all the points unite at the period in which ossification terminates; we see this in the cotyloid cavity, in the condyle of the occipital bone, &c. There is often in the broad bones two well marked periods for their ossification; it is so in those which, like the sacrum and sternum, are developed by a great number of points. These points begin at first to unite into three or four principal pieces which divide the bone; this is the first period; then much later, the union of the pieces takes place; this is the second period. _Progress of the Osseous State in the Short Bones._ The short bones remain in general longer cartilaginous than the others. Often at birth many are still so, those of the tarsus and carpus in particular. The body of the vertebræ is ossified sooner; a point is developed at the centre, and extends over the whole surface.