ee LECTURE If. 



sidered as characteristic of that fluid befjins 

 to be added. Though blood is so subtile 

 a fluid as to be capable of permeating the 

 minutest vessels of the body, yet that part 

 which spontaneously coagulates, becomes 

 very firm, tough, and unsoluble ; often also 

 assiHTiing a fibrous appearance. From the 

 exact similarity of these fibres to those of 

 which muscles are chiefly composed, which 

 Mr. Hunter has taken great pains to exhibit 

 in preparations you will observe in the 

 Museum, he inferred their identity j an in- 

 ference which modern chemistry has since 

 established. 



With respect to animals, Mr. Hunter 

 observes in M.S. 1776, " In the more 

 imperfect animals, it is very probable 

 that there are no fixed parts, but that all 

 parts are irritable and have motion, like 

 the urinary bladder or an intestine. As 

 animals become complicated, and have 

 various motions, especially the progressive, 

 then such motions are more divided or par- 

 tial ; for which purpose it is necessary there 

 should be substances whose firmness and 



