XVlJ NERVE-ENDINGS IN MUSCLE 127 



4. Fixing the. metJiylene blue stain. Preserve a specimen in each 

 of the two following ways (cp. also p. 322) using the sartorius for 

 (a) and the mylohyoid for (&). 



(a) When the nerve-endings are distinct under a low power, pin 

 out the muscle with hedgehog quills, and place it in a saturated 

 aqueous solution of picrate of ammonia for an hour or more, then 

 tease out and mount in a mixture of equal parts picrate of ammonia 

 solution and glycerine free from acid. 



(6) Place in picrate of ammonia solution as in (a), but after 

 15 minutes 



Transfer it, without washing, to the following solution, 



Ammonium molybdate 1 gram 

 Distilled water 20 c.c. 



Hydrochloric acid 1 drop, 



and leave for 1 to several hours. Wash with water, pass through 

 alcohols, and xylol, and mount in balsam. 



It is advisable to squeeze as much blood as possible out of the frog 

 immediately after pithing it. After noting the mylohyoid in position 

 as above, the jaw may be cut off, pinned out on a ring of cork with 

 the tongue uppermost, the tongue removed and the mucous membrane 

 of the mouth removed; the mylohyoid will thus be obtained stretched. 



5. End plates. Rat. Expose the intercostal muscles of a rat 

 immediately after death, carefully tear and cut away the external 

 intercostal muscles for a centimetre or two between two costal 

 interspaces. Cut out the ribs with the internal intercostal 

 muscles between them and pin out with hedgehog quills. Flood 

 with 25 p.c. formic acid, leave five to seven minutes, then pour 

 a little 1 p.c. gold chloride over the muscles ; in about a quarter 

 of an hour cut out and place in 1 p.c. gold chloride solution, 

 leave for hour. Wash well with water, place for a day in 

 50 p.c. formic acid in the dark 1 . 



Cut the muscles away close to the ribs, put in formic glycerine 



1 The muscle may be transferred to undiluted formic acid for a 

 day. This will sometimes decolourize the muscles, but leave the 

 nerves stained. 



