44 ELEMENTARY HISTOLOGY. 



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. Tease in glycerine a small piece of craVs 



muscle that has been hardened in alcohol ; cover^ and 

 examine with both low and high powers : note : — 

 i. The elongated fibres of which the muscle consists. 

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

 delicate elastic sheath — the sarcolemma — which 

 wall 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. Tease gently apiece of fresh frog^ s muscle 



in normal 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 ivhich has been 

 ^macerated in Ranvier^s alcohol for 2Jf hours ; 2~>encilled with a fine 

 brush to remove the epithelium of the ijiner surface ; stai?ied, and 

 cleared ivith oil of cloves. Mount in balsam, and examine with 

 low and high powers : note : — 



i. The bands of muscular fibre, 

 ii. The formation of each band by a number of 



elongated, fusiform, nucleated muscle-cells, 

 iii. The absence of transverse striation in the muscle. 



