ON THE BONES OF ANIMALS. 



409 



dead bone, and fpotted with red oiTeous nuclei ; proving that 

 the regeneration of the bone had commenced at this early pe- 

 riod. 



In feven days the new bone was found foft and flexible, not — '" regenera- 

 lo be diftinguiflied from cartilage or griftle, except by the red 

 tint the madder had communicated to it ; yet the bone deftroyed 

 was not at all coloured, although the other bones of the animal 

 bad acquired a bright red. From this time the new bone con- 

 tinued to encreafe in hardnefs, furrounding the old one like a 

 ftieath. The latter in about three weeks was fo loofe as to be 

 drawn out, and in about fifteen days from this time, the cavity 

 of the regenerated bone was filled with marrow, and in every 

 refped performed the office of that for which it was a fubfti- 

 tate. This may be confidered as a general outline of the pro- 

 gretlive changes which take place during the regeneration of 

 a cylindrical bone, in a young animal, fuch as a pigeon, or 

 chicken ; and the fame procefs is frequently performed in the 

 human body, when, from fome internal caufe, the life of a 

 bone is deftroyed. Thefe changes involve many interefting 

 particulars; but the circumftance raoft immediately connefted 

 with the fubjed of this paper is, that although the fliaflof the Inference, 



bone required three weeks for its renewal, yet in feven days?^'^°'" the very 



. . ipeedy acquifi- 



(he offeous (yflem generally had acquired a bright red. Now tion and fubfe- 



if we explain this change in colour according to the common 1"e"t lofsof the 



r , r ■ I- , , - , , /> • r , i red colour that 



opmion or abiorption or the white, anddepoution or the red the ofTeous fyf- 



■ofleous matter,* we niuft necetlarily draw this conclufion; that tem was natura!- 



theotfeous fyftem of the animal will be renewed three times J^^^^^^J^^^^jJ^'^j 



during the period, which the formation of the fubftitute bone period. 



requires; a conclufion which we (hould be inclined to rejedl 



merely from its improbability. But befides tliis, th.e appcar- 



* The common opinion of phyfiologifts, with regard to this cu^ 

 rious faft, is, that when a bone becomes red, during the exhi- 

 bition of madder root, the white ofleous particles which compoled 

 It, have been entirely removed by abforption and replaced by new 

 offeous matter of a red colour: and when a bone affbmes its na- 

 tural colour, thefe red particles have been removed and replaced by 

 white. If this be the fa£t, it neceflarily follows, that an animal 

 has at leaft fifty-two new fets of bones in a year; for the ofleous 

 fyftem, according to the experiments of the motf refpeftable phy- 

 fiologifts, acquires a deep red tint from madder in one w^ejc, and 

 affumes its natural colour in another. 



9ne$ 



