XVI] NERVE-ENDINGS IN MUSCLE 131 



The muscle spindles are perhaps most easily found in the 

 intrinsic muscles of the manus and pes. The characteristic 

 annulo-spiral form is much more marked in dog and cat than 

 in rabbit or rat. In man, a portion of the biceps near the 

 entrance of the nerve may be taken. 



In the sterno- cutaneous and other muscles of the frog, 

 muscle spindles also occur, but they are not easy to find. The 

 spindle usually contains two or three muscle fibres ; the nerve- 

 ending consists of fine varicose filaments running for a con- 

 siderable distance along the fibres. 



Hcematoxylin method (Sihler}. A strip of muscle about 

 4 mm. thick, or the whole of a small muscle, is placed for 

 | to 1 day in a macerating fluid composed of 



Ordinary acetic acid 10 c.c. 

 Glycerine 10 c.c. 



1 p.c. chloral hydrate 60 c.c. 



The pieces are placed in glycerine for an hour or two, they are 

 then separated into thin strips and placed 3 to 10 days in the 

 staining fluid, which is the same as the macerating fluid except 

 that 10 c.c. of hsematoxylin takes the place of the acetic acid. 



After staining, the strips are placed in glycerine till required, 

 the glycerine being now and then renewed. For investigation 

 the tissue is differentiated in a mixture of equal parts of glycerine 

 and acetic acid, or more rapidly in acetic acid alone. It is then 

 examined as given in the text 9. 



The muscle may be cut into thick sections with a freezing 

 microtome before being placed in the macerating fluid ; in this 

 case teasing out in glycerine is not necessary. The spindles 

 when cut out may be washed in water, hardened in Miiller's 

 fluid, imbedded and sections stained on the slide. In investigating 

 degenerated fibres the spindles after hardening with Miiller's 

 fluid may be treated by the Marchi method (cp. p. 246). 



N euro-tendinous organs. The nerve-endings of these are 

 stained in the same way as other nerve-endings. 



They are most easily found in the tendinous fascia of the 

 back muscles, and in the deep tendon of the gastrocnemius in 



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