MUSCLE 155 



C. Muscle. 

 In muscular tissue the component cells are much elongated 

 and, in the higher forms, very highly specialised. Muscular 

 tissue is of two kinds : (1) striated, or voluntary, of which all 

 muscles that are under the control of the will consist : and (2) 

 non-striated or involuntary, forming those muscles over whose 

 contractions the will has no direct control. The muscular tissue 

 of the heart, which though involuntary is striated, forms the 

 chief exception to this rule. 



I. Striated, or Voluntary Muscle. 



a. Crab's muscle. Shred in glycerine a small piece of oraVs 



muscle that has been ha/i-dened in alcohol ; cover, and 

 examine with hath low and high powers : note : 

 i. The elongated iibres of which the muscle consists. 

 Each fibre is a single cell, and is enclosed in a 

 delicate elastic sheath— the sarcolemma — which 

 will be visible in but few cases ; it is most readily 

 seen at places where the fibre has been torn 

 across. 

 ii. The alternate light and dark bands with which the 

 muscle fibres are marked transversely, and from 

 which the name, striated muscle, is derived, 

 iii. The readiness with which the fibres split up longi- 

 tudinally into fibrils. 



b. Frog's muscle. Shred gently apiece of fresh frog's muscle 



in nwmal salt solution : cover, and examine with the 

 high power : note : 

 i. The transverse striations. 

 ii. The sarcolemma : best seen by slightly crushing 



the specimen, 

 iii. The nuclei in the fibres : seen on addition of acetic 

 acid. 



II. Non-striated, or Involuntary Muscle. 



Take a prepared specimen of frog's bladder which has been 

 macerated in Eanvier's alcohol fm- 24 hours ; pencilled with afine 

 brush to remove the epitlieliuTn of the inner surface ; stained, and 

 cUa/red with oil of cloves. Mount in balsam, amd examine with 

 low and high powers : note : 



