MUSCLE. 355 



union of the cells is going forward, a deposit of contractile 

 material gradually takes place within them, commencing on 

 the inner surface, and advancing towards the centre, till the 

 whole is solidified. The deposition occurs in granules, which, 

 as they come into view, are seen to be disposed in the utmost 

 order, according to the two directions already specified. 

 These granules or sarcous elements being of the same size as 

 in the perfect muscle, the transverse stripes resulting from 

 their opposition are of the same width as in the adult ; but 

 as they are very few in number, the fibres which they com- 

 pose are of corresponding tenuity. From the very first 

 moment of their formation these granules are parts of a mass, 

 and not independent of one another; for, as soon as solid 

 matter is deposited in the cells, faint indications of a regular 

 arrangement in granules are usually to be met with. It is 

 common for the longitudinal lines to become well defined 

 before the transverse ones : when both are become strongly 

 marked, as is always the case at birth, the nuclei of the cells, 

 which were before visible, disappear from view, being shrouded 

 by the dark shadows caused by the multitudinous refractions 

 of the light transmitted through the mass of granules ; but 

 they can still be shown to exist in the perfect fibre, in all 

 animals, and at all periods of life, by immersion in a weak 

 acid ; which, while it swells the fibrous material of the 

 granules, and obliterates their intervening lines, has no action 

 on the nuclei." 



According to the views entertained by the author, a 

 striated muscular fibre, in the earliest period of its develop- 

 ment, consists of cells arranged in linear series : these unite 

 together, giving origin to *the fibrilla and not the fibre, and 

 that each fibrilla of a fibre is, in like manner, developed from 

 cells. 



Dr. Sharpey, in the fifth edition of Quain's Anatomy, makes 

 the remark, in treating of the subject of the development of 

 muscle, " But much still remains to be explained by future 

 investigation." The truth of this remark it is conceived is, 

 in some degree, exemplified in the foregoing article on mus- 

 cular fibre. 



