41 



LESSON XI. 



MUSCLE. 



(a) Fresh Striped Muscle. 



Tease a small shred of muscle taken from the leg of a frog in 

 normal salt solution. 



Study first under low power. Observe the long cylin- 

 drical fibres showing a transverse striation. Move the 

 the slide about and you will find broken fibres, the broken 

 ends of which are often united by the sarcolemma. Cause 

 a few drops of a 1% solution of acetic acid to flow under 

 the cover glass, and in a few moments the muscle nuclei 

 will be seen. Make a sketch showing the sarcolemma; 

 also a small segment of a muscle fibre showing muscle 

 nuclei as seen under high power. 



(b) Teased and Stained Striped Muscle. 



Small pieces of a striped muscle were macerated for about 24 

 hours in Sihler's macerating fluid, then transferred to glycerine for 

 several hours, and stained in Sihler's heematoxylin for several days. 

 Tease carefully in gum glycerine. 



Study under low power. The cross striations are very 

 clearly seen, also the muscle nuclei. Sketch as seen under 

 low power. 



(c) Branched Striped Muscle Fibres. 



The posterior free end of a frog's tongue was macerated for 

 several hours in M. Schultz's mixture, and stained in hsematoxylin. 

 Tease a small portion in gum glycerine. 



When a voluntary muscle fibre is inserted into a mu- 

 cous membrane or the epidermis, the end so inserted is 

 often branched. This preparation, if you have teased it 

 carefully, will show you these branched fibres. Sketch un- 

 der high power. 



