SKELETON. 379 



was formed of two, three, or four different ossifications. It would be 

 much more proper to give the bone only one name, as, for instance, the 

 • os innominatum,' for two reasons ; because the whole is really but one 

 bone, and because it was formed in one cartilage 1 . This last would be 

 no reason if we found that Nature sometimes formed two bones in one 

 cartilage, and that they remained so through life ; but this is never the 

 case. However, we have an exception to distinct cartilages forming 

 distinct bones ; for the sacrum is one bone, although formed in several 

 distinct cartilages, these being closely united together by substances 

 which readily ossify. 



Bones in young animals are often so soft, that they are not able to 

 support the perpendicular weight of body; therefore they generally 

 bend ; those that soonest give way are the tibise and fibulae. The 

 direction in which they do bend is not constant ; being sometimes 

 forward, and often outward. "When forward, it is generally higher up 

 than when outward ; for when outward it is generally just above the 

 ankle: but this bend forward is not altogether from perpendicular 

 pressure ; the tendency to it is assisted by the contraction of the muscles 

 behind. This bend, in the human subject, is produced gradually by 

 pressure from above. That it is from pressure or some power applied 

 beyond the strength of the animal or part, is evident from the case of a 

 young leopard. It was chained by a chain about a yard long, and had 

 always a vast desire to go out of the door : in all its efforts to get loose 

 it pulled in one direction, pulling with one fore-leg, and pushing with 

 the other, by which means the bones of the leg that he pushed with 

 were bent outwards, exactly answering these two motions of the legs, 

 and the motion of the animal. 



Ossification of the cylindrical bones is supposed to begin like a ring 

 in the middle of the cartilage ; and this ring becoming broader, makes 

 the length of the bone. But I have reason to believe this is only con- 

 jecture, arising from what a section of a cylindrical bone would show. 

 For in a very young bone we never find the end of it hollow, although 

 the middle of it may be so ; but as the end increases in length, from 

 being solid, it becomes hollow ; this scooping out or excavation follow- 

 ing the growth. 



Cut off from the end of an older bone the proportion by which it 

 exceeds the length of a younger one, and we shall find the cut end of 



1 [Hunter, it will be seen, fails to appreciate the signification and value assigned 

 in homological anatomy to the distinct points of ossification in the common carti- 

 lage of the compound bones which he cites. It is interesting, however, to find this 

 approach to the verge of considerations which have subsequently exercised so 

 strongly the anatomical mind.] 



