AGE. 



79 



and the outer plate has approximated and 

 indeed become identified with the inner; 

 hence we see more depressions on the surface 

 of an aged skull. 



On inspecting the internal structure of these 

 organs, we find the cavities that contain the 

 marrow much more extensive than formerly, 

 and the medullary tissue reduced to a con- 

 sistence scarcely exceeding that of oil. The 

 cells also of the short bones and of the ex- 

 tremities are more expanded, and the laminae 

 which form them are very much attenuated. 



The deficiency of animal matter renders the 

 bones of the aged fragile ; they are broken by 

 the most trivial accidents. It is also the cause 

 of their slowness to unite ; for the activity of 

 assimilative, and consequently of reparative 

 processes, is dependent on the vascularity and 

 fluidity of a tissue. The lightness, however, 

 of these organs produced by the same cause is 

 beneficial, or at all events in harmony with the 

 state of the muscular system. 



If we next turn our attention to the ar- 

 ticulations, we shall find that similar pro- 

 cesses of disqualification for former functions 

 have ensued. The spinal column, which 

 once adapted itself with such ease and flexi- 

 bility to the motions and curves of the 

 body, has become almost as rigid as a single 

 bone by the drying up of the intervertebral 

 cartilages, and sometimes by the encroach- 

 ments of ossification.* Scarcely any traces of 

 cartilages between the ribs and the sternum 

 can now be found ; one of the causes to which 

 we alluded above, in connection with dimi- 

 nished respiration. The same deficiency of 

 cartilage is observable in the bones of the wrist 

 and of the tarsus. A change, the opposite of 

 mobility, may also be detected in the liga- 

 ments which embrace the joints; they are 

 dense, dry, and inelastic. The gelatine which 

 enters so largely into their composition has 

 become altered in its chemical properties; 

 it is less easily soluble in water, and has all 

 the characters of glue rather than of jelly. 

 Ill-adapted as this state of the articulations is 

 to the purposes of motion, it is, we think, not 

 altogether difficult to discern its appropriateness 

 to the human being at this advanced period. 

 Were the joints supple and flexible, while the 

 muscles have so little power, how much 

 greater would be the risks of accidents to the 

 aged man in the slight motions which he 

 achieves. In order to preserve their frames 

 from falling, those whose joints move easily 

 upon each other are compelled to exercise those 



*' Cependant il est rare que les fibro-cartilages 

 s'ossifient chez les snjets avances en age. A la 

 verite on voit souvent les vertebres se reunir avec 

 les autres au moyen d'une substance osseuse, mais 

 cette souture depend bien plus rarement de 1'ossi- 

 fication des fibro-cai til ages que de la formation de 

 lames osseuses a la circonference des deux faces 

 par lesquelles se regardent les coups des vertebres. 

 Cependant j'ai observe quelquefois aussi 1'ossifica- 

 tion des fibro -cartilages intervertebraux, et j'ai 

 trouve alors, en sciant longitudinalement la colonne 

 epiniere, que plusieurs vertebres etaient soudees 

 ensemble, et confondues en une seule masse." 

 Meckel, Manuel d'Anat. t. i. p. 364, 



muscles which keep the limbs in the requisite 

 degrees of extension and stability, during cer- 

 tain attitudes and motions; but this end is 

 accomplished in the feeble old subject by the 

 very stiffness of his articulations. 



The muscles are subject to changes no less 

 decided than those in the organs just men- 

 tioned. They are pale, flabby, atrophied, and 

 indisposed to contract on the application of 

 stimuli ; but the fibre itself is tough and not 

 easily torn, and the true muscular substance 

 seems to have given way in some places to a 

 sort of dense cellular membrane, or a yellow- 

 ish degeneration of tissue particularly de- 

 scribed by Bichat, Their tendons are often 

 studded with calcareous matter, and the sheaths 

 in which they play are rigid and unmoistened 

 with synovia. They obey the stimulus of the 

 will tardily and irregularly ; the uncertain 

 tremulous movements, the tottering gait, the 

 stooping posture, the unsteady grasp of the 

 aged, are familiar to every one. 



The organ of voice comes next to be con- 

 sidered. The larynx, once composed of seve- 

 ral cartilages that moved freely on each other, 

 is now a cavity capable of much less variation 

 in its dimensions, owing to the rigidity of its 

 parietes; the extent of the cavity gives in early 

 old age that depth of tone, which by its gravity 

 and solemnity excites our homage. In more 

 advanced age, however, the tone becomes 

 hoarse, shrill, and piping; this in all pro- 

 bability is produced by the contraction and 

 stiffness of the rima glottidis, but still more 

 by the want of vigour in the muscles of the 

 mouth and throat. The incapability of ma- 

 naging the tone, and the tremulous articu- 

 lation, are also results of changes in the muscles 

 of the larynx, pharynx, and tongue, similar to 

 those which transpire in other parts of the 

 muscular system. Many senile impediments 

 of speech are also produced by the loss of 

 teeth, by the falling in of the cheeks, and by 

 the disproportion of the lips to the space which 

 they occupy. 



In our investigation of the signs of decay in 

 the parts that are subservient to sensation 

 and thought, we shall be met by the same 

 difficulties which formerly opposed our way, 

 when inquiring into the phenomena of their 

 development. We traced the progress 'of the 

 nervous substance both in the nerves and in 

 the cerebro - spinal centre from the almost 

 pulpy state recognized in the infant, to its firm 

 consistence in the adult. If we now inves- 

 tigate the anatomical quality presented by the 

 tissue in advanced life, we shall find that it 

 has shared the alteration of nearly all the other 

 tissues, that in short it has increased in density. 

 This fact viewed in connection with another, 

 namely, that ramollissement and induration 

 produce very nearly the same lesion of func- 

 tion, will account for the failure in the sensific 

 powers of old age. Besides this alteration in 

 the substance of the nerves, they are found to 

 be diminished in diameter ; their neurilemmes 

 are become, like other membranous parts, much 

 harder and stronger. Moreover, Bichat has 

 remarked that the nervous tissue of old ani- 



