THE MUSCULAR TISSUE. 



in c, a fibre splits into transverse discs opposite the intervals between 

 corresponding rows of sarcous elements. When a single fibrilla is 

 very highly magnified, its component row of oblong sarcous elements 



Fig. 25. 



Fig. 25. a (The Author), a small muscular fasciculus, composed of parallel prismatic muscular fibres, 

 marked with cross lines or striae ; one of the fibres is split into the finer threads called fibrillae or filaments. 

 b (Kolliker), two muscular fibres, one broken inside the tubular sheath called the sarcolfmma. c (after 

 Bowman), a single fibre more magnified, showing the longitudinal and transverse striae ; also the lateral 

 adjustment of the sarcous elements of its component fibrillse, which explains the cross striae ; and the occa- 

 sional cross splitting of a fibre between rows of sarcous elements into discs, d (Bowman), a muscular fibre 

 partly in a state of rest, and partly (to the left) in a condition of contraction, e (Kolliker), mode in which 

 a muscular fibre changes, in becoming attached to, or continuous with, the fibrous connective tissue Of ten- 

 dons or periosteum. /(Kolliker), oblique insertion of muscular fibres into tendon, a, b,d and e are mag- 

 nified about 150 diameters, c 300, and/ 70 diameters. 



presents alternate dark doubly-refracting, and light singly-refracting 

 quadrangular portions, in the latter of which a delicate cross line is 

 sometimes seen. The dark portions have been described as crystal- 

 line, and as being composed of minute doubly-refracting particles, 

 named disdiaclasts. 



In the formation of muscles, the fibres are collected into minute 

 fasciculi or bundles, #, named the smallest fasciculi, which, again, are 

 gathered parallelly into larger bundles, and these into still larger ones, 

 as shown in Fig. 26. Each muscle is invested by a sheath of areolar 

 tissue, named the perimysium, from which fine partitions of the same 

 tissue, supporting the bloodvessels and nerves, pass inwards between the 

 fasciculi and fibres. Most of the muscles are fixed to the bones, either 

 directly or indirectly, by means of tendons; but, even in the former 

 case, the individual muscular fibres are attached to the bone indirectly 

 through the fibrous tissue of the periosteum. Some muscles, however, 

 are fixed to soft parts, as to the tongue, lips, and eyeballs ; either 



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