( 129 ) 



I HAVE made many obfen'-ations to difcover the real formation 

 t)f the Bones, and in my latell oblervations on the folid part of an 

 ox's thigh Bone, I plainly faw that it conlill:ed of four different 

 kinds of tubes, running lengthways in the Bone, the leall of which 

 are fo fmall, and lie fo clofe together, that they cannot eafily be 

 diftinguillied in a Bone cut tranfverfely ; and even if the Bone is 

 cut with the fharpeft knife that can be had, nothing will be (een 

 but the appearance of globules ; but if the Bone is fplit or cleft, 

 fomc fragments will be broken off in which thofe fn^iU tubes will 

 be perceived. 



The next kind of tubes (fome of which are four, fome fix times 

 larger than the former) are likewife not eafily difcovered ; becaufe, 

 let the knife we cut them with be ever fo fharp, the hardnefs of the 

 Bone will caufe many pieces to be broken off, which, for the 

 greateft part, will clofe up or conceal the mouths or openings of 

 thofe tubes. 



The third fort of tubes, which are much larger than the lafi^, 

 will become lb fiopped up in the cutting with a knife, that it will 

 be difficult to difcover their cavities ; but I have obferved thefe tubes 

 lying difpofed in fuch a manner, that I was well aflured a circle of 

 thofe tubes formed every new concretion or addition to the Bone, 

 almoft in the fame manner as I have laid it down in regard to the 

 growth of timber, by the addition of a circle or ring of tubes, 

 formed in the growth of the wood ; and efpecially when I faw, 

 that in a fmall fpace from thence, another circle of tubes was to 

 be feen. 



The fourth kind of tubes, flill much larger than the lafi: preced- 

 ing, were fewer in number, fo that often, in the fpace of three or 

 four grains of fand, I could not fee one of them. 



I have made as exadl a di-awing as poflible of a fmall jiarticle, 

 taken from an ox's thigh Bone, as the fame appeared to me through 

 the microfcopc, and which is fliewn at j^V. 14, ABCD. This 



YOL. II. Il 



