on the Bones of Animals, 15^ 



pcarances indicate, when explained in the 

 common way ; is completely at variance witli 

 all the processes performed by the boi^s, both 

 in their healthy and diseased states. Thus we 

 find the formation of the ossific matter, called 

 Callus, for the union of fractured bones; or 

 the exfoliation of a part of a bone, are processes 

 requiring a considerable length of time for 

 their performance. In Dr. M'Donald's ex- 

 periments, the formation of a regenerated bone 

 required nearly six weeks ; but during the 

 same space of time, the bones of the same 

 animal would be renewed several times, if the 

 common explanation of the communication 

 and disappearance of the tinge of madder were 

 well founded. From these circumstances, I 

 am led to believe, that the appearances pro- 

 duced by the exhibition of madder, require 

 another mode of explanation. That which I 

 have to offer is not liable to the same ob- 

 jections, and is strongly supported by com- 

 parative experiments. 



It was observed by Du Hamel, in hi^ ex- 

 periments, that the bones of animals, which 

 had been deeply tinged by madder, by long 

 exposure to air lost their colour and became 

 white, it was this fact which suggested to me a 

 simple explanation of the process. It occurred 

 to me, that if any one of the component parts 



