452 MOVEMENTS. 



sand. 1 The structure of the fibrillae, which are regarded by 

 many as the anatomical elements of the muscular tissue, has 

 been very closely studied by Rouget ; and, although all of 

 his observations, particularly those with regard to the spiral 

 form of the fibrillae, have not been confirmed, there can be 

 hardly any doubt that their structure is uniform, the appear- 

 ance of alternate dark and light segments being due to dif- 

 ferences in thickness. 2 In fact, it is well known that water, 

 by its simple mechanical action, swells the fibrillge, and 

 causes the striae to disappear. 



Late researches have shown that the interior of each prim- 

 itive fasciculus is penetrated by an excessively delicate mem- 

 brane, closely surrounding the fibrillse. This arrangement 

 may be distinctly seen in a thin section of a fibre treated 

 with a solution of salt in water in the proportion of five 

 parts per thousand. 3 The arrangement of this membrane, 

 which is nothing more nor less than a series of tubular 

 sheaths for the fibrillae, is a strong argument in favor of the 

 view that the fibrilla is the anatomical element of the mus- 

 cular tissue. 



By the action of certain reagents, such as alcohol, hydro- 

 chloric acid, or gastric juice, the primitive fasciculi may 

 be separated into disks corresponding to the transverse striae. 

 Bowman, in his elaborate investigations into the structure 

 of the muscles, noted this fact, and concluded that the cleav- 

 age in this direction was as easily effected as the separation 

 into fibrillae. He regarded the primitive fasciculi as com- 

 posed of fibrillae, and these as made up of little particles, 

 alternately dark and light, w r hich he called sarcous ele- 

 ments. 4 Subsequent investigations, however, have not en- 



1 KOLLIKER, Elements tFhistologie humaine, Paris, 1868, p. 207. 



2 ROUGET, Sur les phenomenes de polarization qui s'observent dans quelqucs tis- 

 sus. Journal de la physiologic, Paris, 1862, tome v., p. 263, et seq., and Memoire 

 sur les tissus contractile^ et la contractilite. Id., 1863, tome vi., p. 647, et scq, 



3 KOLLIKER, Elements d } histologie humaine, Paris, 1868, p. 201. 



4 BOWMAN, On the Minute Structure and Movements of Voluntary Muscle. 

 Philosophical Transactions, London, 1840, p. 457, et seq. 



