260 The Microscope. 



13. Sarcolemma. — In a few cases a marked coiTugation of 

 the sarcolemma was seen (Fig. 52), and when focusing on the edge 

 of the liber the appearance was presented of a process extending 

 from the bottom of each corrugation toward the sarcous substance, 

 and joining the narrow, dark stria in the hght disc of the fiber. 

 This appearance is often seen in insect muscle. 



In all the animals examined, instances were found where the 

 sarcolemma appeared to extend as a tube beyond the sarcous sub-" 

 stance at both the tendinous and intramuscular end of the fibers. 

 This tubular appearance is as marked at the ends as when, in the 

 middle of a fiber, the sarcous substance is torn and retracted, 

 leaving the sarcolemma to bridge the interval (Fig. 44). In a few 

 fine tapering ends from the tongue (Fig. 48), oesophagus (Fig. 46) 

 and skin of the mouse and bat, and also in a few intramuscular ends 

 from the trunk or limbs this appearance was seen, the striations 

 gradually became fainter and disappeared, while the sarcous sub- 

 stance itself, which in the body of the fiber has a distinct color, 

 gradually disappears, or at least loses its color, within the prolonga- 

 tion of the sarcolemma. In some cases, on tapering intramuscular 

 ends or the blunt ends from the tongue and oesophagus, the 

 sarcolemma apparently gives ofP filiform or sometimes nearly 

 spherical processes in which the sarcous substance, if present at 

 all, is not striated (Figs. 3, 11 and 27). At the tendinous end of 

 fibers from many muscles, from all the animals examined, and 

 prepared by nitric acid or caustic potash, especially when the end 

 is somewhat truncate, the tubular prolongation of the sarcolemma 

 seemed very clear, the end of the sarcous substance within it 

 always having a delicately fringed appearance (Figs. 50-51). 

 Tendinous ends seen in situ, as in the rectus abdominis (Fig. 47), 

 give the same impression. In caustic potash preparations the 

 tubular prolongation is less frequent, but a sharp line is often seen 

 encircling the end of the fiber, as though the sarcolemma at this 

 point had been torn, leaving the fringed sarcous substance extend- 

 ing a trifle beyond it. The divisions into which some tendinous 

 ends break up 'Fig. 6 and PI. X), and the branches of intramus- 

 cular ends (Figs. 12-13), do not give the impression of being 

 bounded by a definite membrane at their tips as at their borders, 

 but seem to cease in an indefinite way, generally in the form of a 

 fringe. 



14. Nuclei. — In general the nuclei are more numerous in 

 proportion to the volume of the fiber at both the tendinous and 



