TISSUES OF THE BODY. 



287 



fresh, living muscle fibre; they rather indicate a tendency, on the part of 

 the muscular element, to split up in one of these two directions (2). It 

 must be allowed, however, 

 that the tendency to break 

 up into fibrillse in a longi- 

 tudinal direction is greater 

 than in the transverse into 

 disks, the latter being of 

 rarer occurrence than the 

 primitive fibrillae. 



The supposition of the 

 existence of these sarcous 

 elements, connected longi- 

 tudinally and transversely 

 with one another, neces- 

 sitates of course the pre- 

 sence of a uniting medium 

 between them. And when 

 we remember the com- 

 pletely opposite effect of 

 the two reagents already 

 mentioned, that, for in- 

 stance, very dilute hydro- 

 chloric acid resolves the 

 muscle fibre into plates, 

 while alcohol and bichro- 

 mate of potassium convert it 

 into fibrillse, we must look 

 for two kinds of cement- 

 ing substance, one for 

 the agglutination forming 

 longitudinal fibrillaB, and 

 another different one unit- 

 ing the flesh prisms in a transverse direction and forming disks. The 

 quantity of transverse cement (probably more or less gelatinous) -is far 

 smaller than that of the probably fluid longitudinal. The latter is remark- 

 able for its great capacity for contraction and swelling out. In con- 

 formity with this, we sometimes find the dark transverse zones placed far 

 closer to each other than at other times. 



Here arose the very important question, how the closer relation of 

 the sarcous elements to the transverse lines of the fibre was to be repre- 

 sented. 



We frequently remark (and especially regularly after slight treatment with 

 acetic acid) the transverse striation to be made up of dark zones, refract- 

 ing the light very strongly, alternating with clearer belts of less refracting 

 power. The latter are the layers of the longitudinal cement, swollen up 

 and rendered clear ; while the darker zones represent the sarcous elements, 

 united together by an agglutinating medium, and forming disks. Accurate 

 study of the effect of water acidulated with hydrochloric acid showed 

 how the clear transverse zones become more distinct with the rapidly- 

 commencing swelling up of the longitudinal cementing medium preceding 

 solution ; that a muscle fibre might then break up into disks, each of the 

 latter consisting (like a voltaic element with its zinc and copper plate) of 



tig. '277. 1. A muscle fibre with primitive fibrillae and trans- 

 verse striation strongly marked, taken as the fundamental 

 form. 2. Isolated fibrillae strongly magnified. 3. Sarcous 

 elements united, forming a disk (diagrammatic). 4. Plates 

 of human muscle after treatment with hydrochloric acid. 

 5. A human fibre after prolonged treatment with hydrochloric 

 acid, with dark (c) and light (d) zones and nuclei (a, b). 6. 

 Two pointed fibres from the human biceps brachii. From one 

 of them the interstitial connective-tissue is prolonged over 

 the end. 



