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HANDBOOK OF PHYSIOLOGY. 



space formed of a pellucid substance continuous with them. According 

 to Sharpey, even in a fibril so constituted, the ultimate anatomical ele- 

 ments of the fibre are not isolated. His view was that each fibril with 

 quadrangular sarcous elements is composed of a number of other fibrils 

 still finer, so that the sarcous element of an ultimate fibril would be 

 not quadrangular but as a streak. In either case the appearance of 

 striation in the whole fibre would be produced by the arrangement, 

 side by side, of the dark and light portions respectively of the fibrils 

 (Fig. 277). 



A fine black streak can usually be discerned passing across the inter- 

 stitial disc between the sarcous elements: this streak is termed Krause's 

 membrane: it is continuous at each end with the sarcolemma investing 

 the muscular fibre (Fig. 276 B). 



Thus the space inclosed by the sarcolemma is divided into a series of 

 compartments by the transverse partitions known as Krause's msm- 



FIG. 278. FIG. 279. 



Fio. 278. Three muscular fibres running longitudinally, and two bundles of fibres in transverse 

 section, M, from the tongue. The capillaries, C, are injected, x 150. (Klein and Noble Smith.) 



FIG. ^79. Transverse section through muscular fibres of human tongue. 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.) 



branes; these compartments being occupied by the true muscle substance. 

 On each side (above and below) of this 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. 276, A). 



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

 row of bright granules forming the granular layer of Flogel. The 

 fibres 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 imbedded in 

 a thin, more or less branched film of protoplasm. The nucleus and pro- 

 toplasm together form the muscle cell or muscle-corpuscle of Max 

 Schultze. 



