284 



MANUAL OF HISTOLOGY. 



membrane becomes raised up 'in blebs by endosmosis. Preparations 

 also of the muscles of naked amphibia which have lain in spirit frequently 

 afford very good objects, in which the envelope is observed widely sepa- 

 rated from the included mass. 



On the internal surface of the sarkolemma are situated a series of 

 roundish or oval nuclei (1 d) 0'0074-0'0113 mm. in length. More 

 minute examination of the muscle fibres of naked amphibia (fig. 275) 

 with very high magnifying powers shows the nuclei (c) to be vesicular, 

 with tolerably thick, and therefore doubly contoured walls, and to contain 

 one or two nucleoli. In fresh tissue the nucleus lies closely enveloped 

 in a fusiform cleft. The apices of the latter are occupied by a homo- 

 geneous clear substance. This is the remainder of the original proto- 

 plasm, which has not been consumed in the formation of the fleshy 

 matter of the fibre. This, taken as a whole, has been named the " muscle 



Fig. 274. 1. Striated muscle fibre with a 

 breaking up into primitive fibrillae a; more 

 distinct striat ion at 6, and longitudinal lines 

 at c; d, nuclei. 2. A fibre, 6, torn through 

 at a. with the sheath partially empty and 

 visible. 



Fig. 275. A muscle fibre from the frog, 

 magnified 800 times, a, dark zones with 

 sarcons elements; b, lighter zones; c, 

 nuclei ; d, interstitial granules. (Alcohol 

 preparation). 



corpuscle " (M. Schultze, Welcker), and is looked upon as equivalent to a 

 cell. 



In fig. 275 we may remark filiform streaks springing from these muscle 

 corpuscles, and dotted with fat granules throughout, as also is the 

 degenerated body of the cell. These we shall have again to take into 

 consideration below. 



The number of these nuclei or muscle corpuscles is not inconsiderable ; 

 their position is sometimes without arrangement, sometimes alternating. 

 In the fibres of the heart alone do there exist, beside the circumferential 

 nuclear formations, others which occupy the axis. But among the lower 



