204 STRUCTURE AND ENDOWMENTS OF ANIMAL TISSUES. 



nerves ; and these are derived (for the most part, if not entirely) from 

 the Sympathetic system, rather than from the Cerebro-spinal. 



Fig. 68. 



Portion of Muscle, showing the arrangement of the motor nerves supplying it. 



342. Every Muscular Fibre, of the striated kind at least, is attached 

 at its extremities to fibrous tissue ; through the medium of which it 

 exerts its contractile power on the bone or Bother substance, which it is 

 destined to move. The muscular fibre usually ends abruptly by a per- 

 fect disk ; and the myolemma seems to terminate there. The tendinous 

 fibres are attached to the whole surface of the disk ; and seem to spread 

 themselves from it over the whole myolemma. Thus the whole muscle 

 is penetrated by minute fasciculi of tendinous fibres ; and these collect 

 at its extremities into a tendon. Sometimes the muscular fibres are 

 attached obliquely to the tendon, which forms a broad band that does 

 not subdivide ; this is seen in the legs of Insects and Crustacea, in which 

 the muscular fibres have what is called a penniform arrangement, being 

 inserted into the tendon, on either side, like the laminae of a feather 

 into its stem. The forms which different muscles present, have reference 

 purely to the mechanical purposes, which they have respectively to 

 accomplish. The elements are the same in all, both as regards structure 

 and properties. 



343. Notwithstanding the energy of growth in Muscular tissue, it is 

 doubtful if it is ever regenerated, when there has been actual loss of 

 substance. Wounds of Muscles are united by Areolar Tissue, which 

 gradually becomes condensed ; but its fibres never acquire any degree 

 of contractility. 



344. It is probable that the pure Muscular Fibre is identical in ulti- 

 mate composition, or nearly so, with the Fibrine of the blood. It differs, 

 however, in this : that the fibrine of muscle is soluble in dilute muriatic 

 acid, whilst that of blood swells up without dissolving. The fibrine of 

 veal bears a closer resemblance to that of blood, than to that of adult 

 muscle. In ordinary muscle, the solid matter forms about 23 parts in 

 100 : the remainder consisting of water. The solid matter contains 

 about 7 J per cent of fixed salts. 



345. We now come to investigate the remarkable property, which is 



