ANATOMY OF THE MUSCULAR FIBRE. 



that they are uniaxial, positively refractile bodies, like rock 

 crystal, and that they are made up of groups of still smaller 

 bodies, to which he restricts the term disdiaklasts. During 

 contraction the flesh prisms, or sarcous elements, become 

 shorter and thicker, and if they were single solid bodies, that 

 would imply a strain and change of position of the molecules, 

 which would alter their refracting power. No such alteration 

 takes place, therefore " the form of the whole group that is r 

 of the sarcous element is here changed by an alteration in 

 the arrangement of the several corpuscles, just as in a company 

 of soldiers groups of various breadths and depths are produced 

 by changes in the position of the several individuals" (p. 240). 

 By the more recent researches of Schafer, Flogel, Merkel, and 

 Engelmann ("Medical Record," 1873) we find that the shortening 

 of the rod-layer may amount to two-thirds of its length (Flogel). 

 It is denied that the double-refractile rod-like bodies and the 

 single-refracting intermediate substance are distinguishable 

 during life (Engelmann). Each muscular fibre is divided into 

 a number of equal divisions, each of which contains transparent 

 fluid substance, in which is accumulated at the sides of the 

 median membrane the gelatinous contractile substance, the 

 proper transverse stripe (Merkel). " When a muscular fibre 

 contracts, the individual divisions do not pass at once from the 

 state of rest to that of contraction, but they go first through 

 an intermediate state." This latter is characterized by the dis- 

 appearance of all optical differences, the contents of the muscular 

 division being perfectly homogeneous, and at the same time 

 very bright. "During this state the contractile substance, 

 imbibing all the fluid that is contained in the division, swells 

 so as to fill out this completely, and having gone through this 

 preparatory state, again presses out the fluid and accumulates 

 on both ends of the division beside the terminal disc. The 

 individual particles of the contractile substance press as close 

 as possible to this terminal disc, the former tiying to come into 

 contact with the latter by as many of its particles as possible : 

 in consequence of which the muscular fibre not only becomes 

 broader, but also the fluid which is pressed out by the contrac- 

 tile substance is now accumulated in the middle of the division 



