80 



rect, for the reasons, which I have slated in the? 

 analysis of muscular fibre. 



On the composition of the bones, according tu 

 the different age of the individual, \ve have no 

 satisfactory experiments ; neither do we know 

 the general differences of the bones of different 

 classes of animals. HATCHETT has examined 

 the integuments or coverings of the testacea, which 

 we justly consider as the bones of those animals, 

 and he found them to be composed of a peculiar 

 animal matter, the nature and chemical proper- 

 ties of which he did not minutely determine, and 

 of carbonate and phosphate of lime. While the 

 bones of the mammalia consist of phosphate of 

 lime with but little carbonate, these shells, on the 

 contrary, consist of carbonate of lime with a few 

 p. c. of the phosphate. 



Marrow, or the fat, which is contained in the 

 long bones, appears, by my experiments, to be 

 similar to fat in other parts of the body and the 

 different properties it acquires by being boiled 

 whilst included in the bone, belong entirely to 

 the fluids, contained in the vessels of the proper 

 membrane of the marrow, and which it loses 

 altogether, when the fat is melted from its cells. 



