1026 CHARACTERISTICS OF DIFFERENT AGES. 



bled ; so that any latent predisposition to disease is extremely liable to 

 manifest itself; or the bodily vigor, if for a time retained with little deterio- 

 ration early undergoes a marked diminution. 



873. After the attainment of Puberty, no marked alteration takes place 

 in the organism, save the continuance of its increase in stature, usually for 

 a few years longer ( 784) ; which increase is the chief manifestation of the 

 excess of the germinal capacity, that has not yet expended itself in the 

 building up of the fabric. But so long as this increase is going on, there is a 

 want of that solidity and compactness of the organism which seem only at- 

 tainable when growth has ceased ; and the attainment of which, being essen- 

 tial to the highest manifestations of vigor and endurance, marks the final 

 completion of its development. Of this we have the best illustration in the 

 Osseous system ; whose completion, being postponed until all further growth 

 has ceased, may be fairly considered as marking the final stage in the devel- 

 opment of the organism, and as therefore characterizing the period of Adoles- 

 cence. Commencing with the Vertebral Column, we find that whilst the 

 "body" and "neural arches" of each vertebra become consolidated in early 

 childhood, the spinous and transverse processes are completed by separate 

 "epiphyses," the ossification of which does not commence until after puberty, 

 and the final union of which with the body of the bone may not occur until 

 the age of twenty-five or thirty years. About the same time, there is formed 

 and added to each surface of the body of the vertebra a smooth annular 

 plate of solid bone, which covers a portion that was previously rough and 

 fissured. During this period, the consolidation of the Sacrum is proceeding: 

 the component vertebrse of which remain separate up to about the sixteenth 

 year, and then begin to unite from below upwards, the union of the two high- 

 est being completed by about the twenty-fifth or the thirtieth year; whilst 

 at the same time thin osseous plates are formed on either side of the coalesced 

 mass, which seem to represent the epiphyses of the transverse processes of its 

 component vertebrre, and like them are finally joined on to the body of the 

 bone. The ossification and coalescence of the Coccygeal vertebrre take 

 place at a still later period. Each rib in like manner has two epiphyses, one 

 for the head and the other for the tubercle ; the ossification of which begins 

 soon after puberty, whilst their union with the body of the bone is not com- 

 pleted until some years afterwards. The five pieces of which the sternum 

 consists, though themselves completely ossified, remain separate until after 

 the age of puberty ; when their union commences from below upwards, as in 

 the sacrum, not being always completed, however, even in old age, by the 

 junction of the first piece to the rest of the bone. The ossification of the 

 Eusiform cartilage does not commonly begin until after the age of puberty ; 

 and it is usually not entirely completed even in very advanced life. The 

 ossific union of the separate elements of the Bones of the Skull ( 794,795), 

 is usually completed within a few years after birth ; but there are some parts 

 which not uufrequeutly remain distinct during the greater portion of life, and 

 which may even never coalesce; such is the case with the two halves of the 

 Frontal bone, which often remain permanently divided by a continuation of 

 the sagittal suture, and with the Styloid process of the temporal bone. In 

 the Upper extremities we find the Scapula presenting three epiphyses, one for 

 the coracoid process, one for the acromion, and one for the lower angle of 

 the bone ; the ossification of which begins soon after puberty, their union 

 with the body of the bone taking place between the ages of twenty-two and 

 twenty-five years. The Clavicle has an epiphysis at its sternal end, which 

 begins to form between the eighteenth and twentieth years, and is united to 

 the rest of the bone a few years later. The consolidation of the Humerus is 

 completed rather earlier ; the large piece at the upper end, which is formed 



