MUSCULAR TISSUE. 



181 



4. The muscular tissue of the crayfish always has the 

 form of bands or fibres, of very various thickness, marked, 

 when viewed by transmitted light, by alternate darker and 



Fig. 52. — Astacus fliiciatills. — A, » single muscular fibre, transverse 

 diameter ^th. of an inch ; B, a portion of the same more highly 

 magnified ; C, a smaller portion treated with alcohol and acetic 

 acid still more highly magnified ; D and E, the splitting up of a 

 part of a fibre, treated with picro-carmine, into fibrillse ; P, the 

 connection of a nervous with a muscular fibre which has been 

 treated with alcohol and acetic acid, a, darker, and i, clearer portions 

 of the fibrillae ; n, nuclei ; nv, nerve fibre ; s, sarcolemma ; t, tendon ; 

 1 — 5, successive dark granular stride answering to thfe granular 

 portions, a, of each fibrilla. 



