MUSCULAR TISKUfl. 



181 



4. The muscular tissue of the crayfish always has the 

 form of bands or fibres, of verj' various tliickness, marked, 

 when viewed by transmitted light, by alternate darker and 





Fig. 52. — Astaovs flnciatUis. — A, a single muscular fibre, transverse 

 diameter jigth 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 fibrillae ; F, 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 fibrillse ; n, nuclei ; «», nerve fibre ; s, sarcolemma ; t, tendon ; 

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

 portions, a, of each fibrilla. 



