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HAND-BOOK OF PHYSIOLOGY. 



-each side (above and below) of Krause's membrane is a bright border 

 (lateral disc). In the centre of the dark zone of sarcous elements a lighter 

 band can sometimes be dimly discerned: this is termed the middle disc 

 of Hensen (see Fig. 266, A). 



In some fibres, chiefly those from insects, each lateral disc contains a 

 TOW of bright granules forming the granular layer of Elogel. The fibres 



FIG. 269. 



FIG. 268. Transverse section of a muscle-fibre of water-beetle (hydrophilus pisceus), showing 

 the position of the muscle nuclei. (Walter Pye.) 



FIG. 269. Muscular fibre torn across ; the sarcolemma still connecting the two parts of the fibre. 

 (Todd and Bowman.) 



contain nuclei, which are roundish ovoid, or spindle-shaped in different 

 animals. These nuclei are situated close to the sarcolemma, their long 

 axes being parallel to the fibres which contain them. Each nucleus is 

 composed of a uniform network of fibrils, and is embedded in a thin, 



FIG. 270. 



FIG. 271. 



FIG. 270. Section through the musculac substance of the tongue, with capillaries injected, their 

 meshes running parallel to the fibres. Three muscular fibres are seen running longitudinally, and 

 two bundles of fibres in transverse section, x 150. (Klein and Noble Smith.) 



FIG. 271. Transverse section through muscular fibres of human tongue: the fibres appear in 

 transverse section of different sizes owing to their being more or less spindle-shaped. The muscle- 

 corpuscles are indicated by their deeply -stained nuclei situated at the inside of the sarcolemma. 

 Each muscle-fibre shows the "Cohnheim's fields," that is the sarcous elements in transverse section 

 separated by clear (apparently linear) interstitial substance, x 450. (Klein and Noble Smith.) 



more or less branched film of protoplasm. The nucleus and protoplasm 

 together form the muscle cell or muscle corpuscle of Max Schultze. 



The sarcous elements and Krause's membranes are doubly refracting, 

 the rest of the fibre singly refracting (Briicke). 



