45 



LESSON XII. 

 MUSCLE (Concluded). 



(a) Nerve-Ending in Voluntary Muscle. 



Small pieces of the intercostal muscles of a snake (the inter- 

 costal or any other short muscle of a small mammal may be used) 

 were placed for 10 to 15 minutes in filtere i lemon juice, then hastily 

 washed in distilled water, transferred to a \% gold chloride solution 

 for 15 to 20 minutes, again washed in water, and placed in 20% for- 

 mic acid solution where they remained (protected from the light) 



24 to 48 hours. Tease in glvcerine. 



/k, 

 Study first under low power, and search for a nerve 



fibre terminating in an end plate. The nerve fibre and 

 the branched ending have a purplish color, the muscle a 

 reddish purple. Sketch under high power. 



(b) Isolated Heart Muscle Cells. 



Small pieces of the cardiac muscle of a dog were macerated in 

 a 30% solution of caustic potash for 15 minutes ; the maceration was 

 then interrupted by placing the tissue in a saturated acqueous 

 solution of potassium acetate. Tease in gum glycerine. 



Observe the short oblong cells, one end usually 

 branched. The cells show a cross and longitudinal stria- 

 tion, and possess one, occasionally two, oval nuclei. Draw 

 several as seen under high power. 



(c) Section of Heart Muscle. 



A small piece taken from the ventricle of a dog's heart was 

 hardened in a saturated aqueous solution of mercuric chloride, 

 stained in Delafield's haematoxylin, embedded in paraffin, and 

 sectioned. Fix to slide, and mount in balsam. 



Study under high .power. Note how the cells are 

 cemented into fibres, and these into anastomosing bundles. 

 In cross sections of the muscle the nuclei are seen occupy- 

 ing the center of the cells. Sketch as seen under 4iigh 

 power. 



