50 MUSCLES. 



of these artificial means, it becomes evident that it is 

 composed of two distinct constituents one granular 

 and the other amorphous, the latter being very vari- 

 able in amount, and serving as a connecting medium 

 to the former which is thus imbedded in it. (PL IX. 

 fig. V. 5.) These minute granules the sar cents ele- 

 ments of Bowman (PL X. fig. II. 5), are slightly flat- 

 tened in the direction of the length and breadth of 

 the fibre, and measure, on an average, nnr <rth of a line. 

 These little bodies seem to be the active agents in the 

 production of the contractility of muscle ; it is in 

 them, and in their relation to the amorphous material 

 by which they are enveloped, that we are to look for 

 the power which the muscular fibre possesses of 

 changing its size and shape. 



In fact, according as these ultimate corpuscles 

 approach each other more closely in the direction of 

 the length of the fibre than in the direction of its 

 breadth, it will assume the fibrillated appearance 

 (PL X. fig. II. 4, 5), or, in the opposite case, the 

 appearance of discs piled upon one another. This 

 latter disposition of the sarcous elements presents a 

 more striking appearance, when between the discs 

 which result from their arrangement in transverse 

 rows, a large amount of the amorphous hyaline sub- 

 stance is present, as in fig. V. (PL IX. 5). 



To sum up in a word : the ultimate fibre of striped 

 muscular tissue is composed of an external envelope 

 of simple structureless membrane, which contains a 

 granular material of soft consistence ; and the varia- 

 tions in appearance of the striae by which it is marked, 

 are due to the varying relations which these granules 

 are capable of assuming to each other, 



