O F O L D A G E, 5cc. 471 



which is denominated fat, generally appears at 

 the age of t,^ or 40 years ; and, in proportion 

 as the quantity of it augments, the body lofes 

 • its former lightnefs and freedom of motion; its 

 generative faculty is diminiflicd ; its members 

 turn unwieldy ; and it acquires extenfion at the 

 expence of ftrength and ad:ivity. 



Befides, the bones increafe in folidity; the nu- 

 tritious juices, which formerly ferved to expand 

 the bones, now increafe their quantity of matter 

 only, by filling up their internal cavities; the 

 membranes are changed into cartilages, and the 

 cartilages into bones ; tl.e fibres of the mufcles 

 grow rigid ; the flcin is deprived of its moillure, 

 and wrinkles are gradually formed in it ; the 

 hair turns hoary ; the teeth fall out ; the vifage 

 affumes a haggard appearance, the body bends 

 forward, &c. The firft approaches of this ftate 

 are perceptible before the age of 40 ; they ad- 

 vance by flow degrees till 60, and more rapidly 

 from that to 70, when decrepitude commences, 

 and continues to augment till 90 or 100, when 

 death puts a final period to our exiftencc. 



We fiiall now take a more particular furvey 

 of thefe changes; and, as we have inquired into 

 the caufes of the growth and expanfion of the 

 human body, let us alfo inveftigate thofe of its 

 decay and diffolution. At the commencement 

 of our exiftencc, the bones arc only fmall fibres, 

 of a foft and ductile fubfiancc, and gradually 

 acquire confiftcncc and folidity. They may be 



conlidcrcd 



