378 GENERAL ANATOMY. 



in it previous to birth; and it is one of the latest in being united 

 to the body of the bone. That of the upper extremity of the 

 radius, which is one of the last to ossify, is perhaps, on the 

 contrary, the one which is soonest in uniting. 



598. The growth of the bones takes place in an evident 

 manner, by the successive addition of new bony substance 

 around that which was first formed. 



The growth in length occurs by the elongation of the 

 body of the long bones at their extremities. For this purpose, 

 the ends of the bony cylinder are covered with bony filaments 

 or villosities immersed in the not yet ossified extremity, hol- 

 low and vascular, which continually elongate, becoming more 

 and more slender as the vessels ramify more, and as the ossi- 

 fication slackens. At the same time, the cartilaginous extre- 

 mities, commencing at the centre, are gradually transformed 

 into bones which constitute epiphyses. 



The growth in breadth takes place, in the flat bones, in the 

 same manner, whether by the successive addition of bony sub- 

 stance in the edge of the bone, as in the bones of the skull, or 

 by the osseous formation, under a marginal epiphysis, which 

 covers its edge, as in the scapula and coxal bone. 



The growth in thickness occurs in all the bones in the 

 same manner. The periosteum, which until this period is very 

 vascular, secretes and deposits between its fibres, at the sur- 

 face of the bone, osseous substance, at first mucous, then hard, 

 which being thus successively added to the surface, increases 

 the thickness of the bone. 



599. 'The growth of the prominences of bones takes place 

 in the same manner as that of the long bones furnished with 

 epiphyses, that is to say, between the body of the bone and 

 the base of the eminence; as in the trochanters, &c. In others, 

 it is at the surface itself that the growth occurs, precisely 

 in the same manner as the growth in thickness of the bones. 

 Most of the eminences grow in this way. As to the hollow- 

 ing of the external cavities which are not articular, it is in 

 many places determined by pressures, which without really 

 depressing the bone, nevertheless produce a depression of it; 



