THE STRUCTURE OF MUSCLE. 91 
semi-fluid, but it hardens and becomes solid immediately 
after death. - 
Examined, with high magnifying powers, in this 
Fie. 19.—Astacus fluviatilis.—A, a single muscular fibre ; transverse 
diameter ,},th of an inch; B,a portion of the same more highly 
magnified; C, a smaller portion still more highly magnified ; 
D and BE, the splitting up of a part of fibre into fibrille; F, the 
connexion of a nervous with a muscular fibre which has been 
treated with acetic acid. a, darker, and 0, clearer portions of the 
fibrille ; », nucleus of sarcolemma; nv, nerve fibre; s, sarcolemma; 
t, tendon ; 1—5, successive dark bands answering to the darker 
portions, a, of each fibrilla. 
