ANATOMY. 



ny a crust of cartilage. In this state it 

 is" technically termed an epiphysis. The 

 body, or middle part of the bone, is call- 

 ed the diaphysis. The projecting parts, 

 or processes of bones, are also in many 

 instances originally epiphijses. The time 

 by which these epiphyses are consolidat- 

 ed by a bony union with the diaphysis, va- 

 ries in different bones, but it is not pro- 

 longed in any much beyond the age of 

 puberty. 



AVe perceive an evident advantage in 

 the bones of the foetus being formed as 

 they are. Their flexibility admits of the 

 form of the limbs becoming adapted to 

 the varying figure of the pelvis, through 

 which they must pass ; and their elastici- 

 ty, which is powerful, restores them af- 

 terwards to their natural shape. 



The animal substance contained in 

 bones is demonstrated by immersion in 

 weak acids, which dissolve the earth, and 

 leave a kind of cartilage similar to that 

 in which the bone was originally formed. 

 Long boiling in a close vessel removes 

 the gelatinous substance, which is dis- 

 solved in the water. The earth of bones 

 is demonstrated by calcination, which 

 drives off the animal matter, and leaves 

 the earth alone behind. This earth con- 

 sists chiefly of phosphate of lime ; but 

 there is also a small proportion of carbo- 

 nate of lime. In young subjects the ani- 

 mal substance predominates, and the 

 bone appears redder, in consequence of 

 the arteries being larger and more nume- 

 rous. The bones of old persons contain 

 more earth, and are consequently whiter 

 and less vascular. 



Some recent experiments have shewn 

 the quantity of jelly contained in bones to 

 be much larger than was supposed, and 

 as it forms a very good soup when dis- 

 solved in water, the circumstance is of 

 considerable importance, as furnishing' an 

 article capable of supplying much whole- 

 some nutriment. The quantity of soup 

 furnished from a given bulk of bruised or 

 pounded bones, boiled in a vessel with a 

 closed lid, considerably exceeds that 

 which can be extracted from the same- 

 quantity of meat. Of course the articular 

 heads of bones, and the reticular texture, 

 in general furnish the greatest quantity. 



It lias been generally taught, that bones 

 are composed of fibres and laminx : the 

 fact is, that they consist of a reticulated 

 texture, very similar to cellular substance 

 in other parts of the body. 



According to the obvious differences 

 in their forms, bones are divided into the 

 long and flat. 



Two kinds of structure may be observ- 

 ed in all bones : in the one, the bony 

 substance is condensed, and leaves no in- 

 terstices ; in the other, there is a mere 

 net-work of bony fibres and plates, leav- 

 ing numerous intervals. The latter is 

 termed the cancellous substance of bones. 



The cylinder of a long bone is com- 

 posed entirely of the firmer substance, 

 and in its centre is hollowed out to con- 

 tain the marrow. In those extremities of 

 the bones, which form the joints, which 

 are greatly expanded, in order to increase 

 the extent of surface, there is a thin layer 

 of the compact substance, but all the in- 

 terior is cancellous. In broad or flat 

 bones, the firmer substance is formed into 

 two plates or tables, and the interval be- 

 tween these is occupied by cancelli. 



Many advantages arise from this ar- 

 rangement of the earth of bones. The 

 long bones are made slender in the mid- 

 dle, to allow of the convenient collocation 

 of the large muscles around them ; they 

 become expanded at their extremities, to 

 afford an extent of surface for the forma- 

 tion of joints, and the support of the 

 weight of the body. A cavity is left in 

 the middle; for if all the earthy matter 

 had been compacted into the smallest 

 possible space, the bones would have 

 been such slender stems, as to be very 

 unsuitable to their offices ; and if they 

 had been of their present dimensions, and 

 solid throughout, they would have been 

 unnecessarily strong and weighty. 



The phenomena, which result from 

 feeding an animal with madder; sufficient- 

 ly demonstrate the existence of blood- 

 vessels and absorbents in the bones. 

 There is a strong attraction between the 

 earth of bone and the colouring matter ; 

 by means of which they unite and form a 

 beautiful red substance. The whole of 

 the bones of an animal assume this colour 

 soon after an animal has been taking the 

 madder. If it be left off, the bones in a 

 short time resume their natural white ap- 

 pearance, from the absorption of the red 

 colouring substance. The short time in 

 which growing bones become thoroughly- 

 dyed, and in which again the preternatu- 

 ral tint is lost, prove that even in these, 

 the hardest parts of our frames, there' is a 

 process of removal of old parts, and de- 

 position of new ones constantly going on. 



That bones possess nerves, as well as 

 arteries, veins, and absorbents, cannot be 

 doubted. Although in the natural state 

 they seem to be insensible, they become 

 extremely painful when diseased; and 

 again, a fungus, which is sensible, some- 



