102 PRACTICAL HISTOLOGY [XIII 



5. Tease out a piece of the tendinous ending of a 

 muscle from a frog treated as follows. The frog is 

 pithed, placed in water at 50 to 55 C. and put aside 

 for about fifteen minutes, the skin removed and the 

 muscles placed in 70 p.c. alcohol. Observe (h. p.) the 

 ending of the sarcolemma in the tendon. 



The piece of muscle before teasing may be stained 

 with picrocarrnine. 



6'. Striated muscle of insect. Remove with as 

 little injury as possible one of the thin muscles from 

 the leg of Hydrophilus 1 , tease it out a little without 

 adding fluid, and cover. The fibres will for a brief 

 period be seen in a normal condition. In many, the 

 alternate dim and bright stria? will be very distinct; 

 in others the transverse markings will be more or less 

 obscured by an appearance of longitudinal fibrillation. 

 Occasionally fibres are met with, having only a confused 

 granular aspect. If the preparation has been successfully 

 made, waves of contraction may, at times, be seen to 

 travel along the fibres. 



Examine with the highest power available. 



Where the transverse striation is distinct and the 

 fibre extended, a longitudinal marking is indistinct or 

 not seen in the light band, but is present in the thick 

 disc so that it looks like a series of rods and is 

 indicated in the thin disc by its granular appearance. 



Where the fibre is contracted, it is broader, the 

 discs are much closer together, the edge of the fibre 

 is not a straight line but presents a series of small 



1 If not obtainable, take the large common water-beetle (Dytiscus 

 marginalis), or failing that a cockroach or a fly. 



