1868.] On the intimate Structure of Muscular Fibre. 



71 



On the intimate Structure of Muscular Fibre. 

 By Dr. C- Macnamara. 



[Received 29th March, 1867.] 



I have this evening the honor to lay before the Society the results 

 o£ some investigations I have recently been making regarding the 

 minute anatomy of muscle. 



The muscular system, as is known, has commonly been divided 

 into two classes, the striped or voluntary and the unstriped or 

 involuntary muscle, but I can hardly consent to this division of the 

 subject, because it appears to me that there is really no such thing in 

 nature as a striped muscle, the muscular tissue as it is called, whether 

 voluntary or involuntary, being composed of an homogeneous substance, 

 the characteristic features of which are, that it contracts in obedience 

 to the nervous force, its elements under every conceivable circumstance 

 being arranged in such a manner as best to fulfil the mechanical 

 purposes for which it is intended. Whether we examine it in the lens, 

 in the walls of the blood vessels, intestines, or the heart we find in 

 each instance such modifications in the dispositions of the contractile 

 tissue as are best suited to the work it has to perform. 



It is, however, to the circumstances of voluntary muscle that I am 

 now desirous of drawing your attention. This system forms the bulk 

 of the limbs, and is the medium through which the movements of the 

 skeleton and of the organs of sense are effected. 



Every muscle, whatever its dimensions, is composed of the external 

 case of fibrous tissue from the inner surface of which numerous 

 interlacing fibrous bands are given off, and in this fibrous matrix, 

 the larger branches of the vessels and nerves ramify. These structures,' 

 however, are to be found in every part of the body, and are by no 

 means characteristic of muscle, the fibrous tissue allowing of motion 

 among parts of the body which it also binds together; the vascular 

 being the channels through which nutrint fluid is supplied and effete 

 substances are removed from the organism, and the nerves in the case 

 >f the voluntary muscle are the medium through which the mandates 

 of the will are conveyed to the contractile tissue. It is therefore, to the 

 substance contained within the sheath and filling the spaces between 



