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 b}^ transmitted light, by alternate darker and 



Fia. 52. — Astncvf! fliiriafHi.t. — A, a sing-le muscular fibre, transverse 

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

 mag-nified ; 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 fibrillaj ; F, the 

 connection of a nervous with a muscular fibre which has been 

 treated with alcohol and acetic acid, n, darker, and h, clearer portions 

 of thefibrilte ; n, nuclei ; -nv. nerve fibre ; x, sarcolemma ; f, tendon ; 

 1 — 5, successive dark granular stria3 answering to the granular 

 portions, n. of each fii)rilla. 



