THE HISTOLOGY OF THE STRIPED MUSCLE FIBRE. 237 



Fig. 21 represents a portion of a fibre of Dytiscus stained in heema- 

 toxylin after the action of spirit. It shows an alternation of bright 

 and dim discs, the dim discs stained a deep purple and made up of a 

 series of sarcous elements side by side. Across the middle of the 

 bright discs a granular or transverse line is seen. Fine longitudinal 

 lines, the longitudinal bars of the network, may occasionally be seen 

 crossing the bright discs. 



This account agrees for the most part with that given by Klein 1 as 

 to the structure of muscle. He, however, figures a continuous line — 

 the homogeneous Krause's membrane — in the middle of the bright 

 stripe, and no longitudinal fibrillation in the bright disc. 



Let us consider the influence of the intracellular network in pro- 

 ducing the appearances known as sarcous elements, and Cohnkeim's 

 areas, in the muscle fibre. 



The matrix, or substance which lies in the interstices of the network, 

 is of far greater bulk than the network. It is homogeneous through- 

 out j nevertheless, it may be looked upon as being partially divided 

 into columns or fibrils by the longitudinal bars of the network, and 

 partially into discs — the contents of muscle compartments — by the 

 transverse networks. By the action of spirit the matrix becomes split 

 into fibrils. The reagent causes this " sarcous substance " to shrink 

 (possibly by abstraction of water), and the homogeneous mass now 

 separates into fibrils along the lines of greatest weakness — that is, 

 along the guide lines formed by the longitudinal bars of the network. 

 These fibrils may again divide transversely at the horizontal networks, 

 producing sarcous elements (diag. 8). Thus the appearance of sarcous 

 elements is seen, as described by Klein, 2 to be a post-mortem phenomenon. 

 In consequence of shrinking the sarcous substance no longer entirely 

 fills up the skeleton " muscle caskets," and the division into sarcous 

 elements, which was foreshadowed only before by the bars of the 

 network, becomes evident by the development of intervening spaces 

 between adjacent elements. The appearance known as Cohnheim's 

 areas is somewhat differently described by different observers. For 

 the present we may follow Klein's 3 description. The prismatic sarcous 

 elements which lie side by side in the living fibre with no intermediate 

 substance, shrink through coagulation on dying, and become separated 

 from one another by a transparent interstitial fluid substance. In a 



1 « Atlas of Histology,' p. 77. 

 s Loc. cit., p. 76* 

 3 Loc. cit. 



