278 



OF MUSCULAR CONTRACTILITY. 



into a state of complete contraction, when subjected to excitement of some 

 kind, the very important inference may be drawn, that the property of 

 contractility is inherent in the tissue itself, and is not dependent (as some 

 physiologists have supposed) upon nervous agency, though usually called 

 into action by it in the living body. This inference will be shown to be fully 

 borne out by physiological facts. The result of various experiments made for 

 the purpose, leads to the conclusion, that the total bulk of a muscle in con- 

 traction is not less than when it is in a relaxed state ; or that the difference, if 

 any exist, is extremely trifling. 



373. All muscular fibres are attached at their extremities to tissues of the 

 ordinary fibrous character ; and most commonly to that which is known as 

 tendinous structure. The component fibres of this are arranged, with great 

 regularity, parallel to each other ; and they are attached to the end of the 

 sarcolemma, which terminates abruptly ; so that the muscular fibre does not 

 taper to a point, as some have supposed. The line of demarkation between 

 the muscular and tendinous structure, is always very distinct (Fig. 68). 



Fig. 68. 



Attachment of Tendon to Muscular Fibre, in Skate. After Bowman. 



374. The Sarcolemma of the Muscle, like the tube of the Nerve ( 110), 

 appears to be the part first formed ; being distinctly visible long before any 



[Fig. 69. 



Stages of the development of striped Muscular Fibre ; 1, arrangement of the primitive cells in a linear 

 series, after Schwann; 2, the cells united; the nuclei separated, and some broken up; longitudinal lines 

 becoming apparent. from a foetal calf three inches long; 3, 4, transverse stripes apparent; in 3, the nuclei 

 are internal, and bulge the fibre ; in 4, they are prominent on the surface, from a fcetal calf of two months 

 old; 5, transverse stripes, fully formed and dark; nuclei disappearing from view, from the human infant 

 at birth; 6, elementary fibre from the adult, treated with acid, showing the nuclei, magnified about 300 

 diameters, after Bowman.] 



