FORMS OF MUSCLE. 



of a soft granular material, varying from the -^QQ to 



Fig. 215. Fig. 21C. 



an 



435 



m 



Unstriped fibres. 



Unstriped fibres in acetic acid. 



Fig. 'ill. 



Muscle 

 cells, 



breadth, and exhibiting here and there the traces of Non-stria- 

 nuclei, particularly after the fibre has been acted on by ted fibre - 

 acetic acid, as is shown in Fig. 216. Each fibre may be re- 

 garded as an arrangement of nucleated cells, the nucleus be- 

 ing of a cylindroid or spindle form. The contractile content 

 within is syntonin. Non-striated fibre is not usually attach- 

 ed to fixed points, as to bone, but by being collected into par- 

 allel bundles, different bundles interlacing with one another, 

 contractile planes or surfaces are formed, such as the cylindri- 

 cal coat of muscular structure of the digestive tube, or the 

 contractile layer of the urinary bladder. Similar fibres, im- 

 bedded in the skin and connective tissues, communicate to 

 them the quality of corrugation or contractility. The fascic- 

 uli are bathed externally with an acid juice, characterized by con- 

 taining salts of potash, phosphoric acid, creatinc, nnd inosite. The 

 general appearance of fibre cells of this class is given in Fig. 217 : 

 a is from the small intestine of man ; , from the fibrous invest- 

 ment of the spleen of the dog. (Kolliker.) 



Contractile fibre cells present the following reactions : Acetic 

 acid causes the fibre to swell, and makes the nucleus more contractile 

 visible ; it occasions a complete dissolution when in a fibre - cell s- 

 concentrated state. Dilute hydrochloric acts in a similar manner, 

 the effect in this instance being the same with the fibres of. both 

 smooth and striped muscle. The examinations thus far made have 

 shown no difference in ultimate composition between these forms. 

 The. striated muscular fibre consists therefore of fasciculi, with 

 an elastic investment of sarcolemma, collected into bundles, striated 

 and invested with perimysium. The contractile constituent . fibre - 



