100 PRACTICAL HISTOLOGY [XIII 



b. Add a drop of normal salt solution. " The longi- 

 tudinal granular lines will become more distinct. Some 

 of the fibres may show a distinct longitudinal as well 

 as a transverse striation. 



.Where the bristle was pressed on the fibres, the 

 muscular substance will in some cases be broken, leav- 

 ing a delicate structureless sheath, the sarcolemma, 

 stretching across the gap ; possibly in other places, as 

 where a fibre is bent, the sarcolemma may be seen as 

 a fine bulging line. 



c. Irrigate with 1 p.c. acetic acid ; after a time the 

 shrunken elongated nuclei of the fibres come into view 

 scattered throughout the muscle substance. 



2. Tear off a very small strip of frog's muscle 

 (extended, and then fixed with alcohol), and tease out 

 as finely as possible in dilute glycerine. Note (h. p.; 

 oc. 4) 



The transverse striation is more distinct than in 

 1. Sometimes a very thin dark line, the thin disc, 

 or end disc may be seen in the middle of the light 

 disc. 



A longitudinal striation of the fibres is more or less 

 marked, and some of the fibres have been split up into 

 very fine transversely striated fibrils or bundles of 

 fibrils. Tap the cover-slip ; the longitudinal fibrillation 

 will become more distinct, and some fibres may break 

 across, forming discs. 



3. Longitudinal sections of striated muscle of frog or mammal 



or alcohol) in paraffin. Stain on a cover-slip 

 the iron-hsematoxylin method (cp. p. 287). 

 examine (h. p.) the transverse striation ; 



BRARV 



