22 



GENERAL STRUCTURE OF THE BODY. 



those of motion, while the unstriped occur in the hollow 

 organs, surrounding the cavity and in some cases lessen- 

 ing its capacity by their contraction. 



An intermediate form of muscle known as cardiac 

 muscle occurs in the heart. Here the fibers have stria- 

 tions but the nucleus is generally in the middle of the 

 cell and the fibers branch and run together. 



FIG. 5. Voluntary muscle (Leroy). A, Three voluntary fibers in long sec- 

 tions: a, three voluntary muscle fibers; 6, nuclei of same ;c, fibrous tissue between 

 the fibers (endomysium) ; d, fibers separated into sarcostyles. B, Fiber (diagram- 

 matic): a, dark band; b, light band; c, median line of Hensen; d, membrane of 

 Krause; e, sarcolemma; /, nucleus. C: a, Light band; b, dark band; c, contract- 

 ing elements; d, row of dots composing the membrane of Krause; e, slight 

 narrowing of contracting element aiding in production of median line of Hensen. 



In life muscle appears more or less translucent and 

 is contractile and alkaline, but in death it loses its trans- 

 lucency and becomes rigid, at the same time giving off 

 in decomposition much carbon dioxide, so that its re- 

 action is acid. This phenomenon of the muscles be- 

 coming rigid in death is called rigor mortis and occurs 

 generally a few hours after death, though it may come 



