Huber-DeWitt, Nerve-Endings in Muscles. \y\ 



Nerve ending in muscle spindle : 



Amphibia, frog (Rana halecina) ; 



Reptilia, tortoise (Chrysemys picta and Emys mel- 



eagris) ; 

 Bird, dove ; 

 Mammalia, dog, cat, rabbit, Guinea pig and rat. 



MetJiod: The methylene blue method has alone been used. 

 A 1 % solution of methylene blue in normal salt was injected 

 either into the living animal, or (in staining the nerves in mus- 

 cle spindles, the intrinsic plantar muscles being used almost ex- 

 clusively) into the abdominal aorta after bleeding the animal. 

 From 45 minutes to an hour after the injection, the tissues to 

 be studied were removed to a slide moistened with normal salt 

 solution, where they remained until the blue color was devel- 

 oped in the nerve fibers, this being controlled under the micro- 

 scope. As soon as the nerve endings seemed well stained, 

 some of the pieces of muscle were placed in the following 

 fixative : 



Ammonium Molybdate . 1 grm. 



Aqua Dist lo c. cm. 



Hydrochloric Acid 1 gtt. 



This fixative, which is only very slighly modified from that 

 suggested by Bethe, needs to be cooled to nearly zero, before 

 placing the tissues into it ; it is therefore well to prepare it be- 

 fore the injection is made, and to surround it with ice, so that 

 it may be properly cooled before using. In this fixative, the 

 tissues remain from 6 to 1 2 hours ; they are then washed in dis- 

 tilled water and hardened in absolute alcohol ; embedded in 

 paraffin and cut in serial sections. The sections were fixed to 

 slides with albumen fixative and counter stained in alum car- 

 mine or alum cochineal and mounted in balsam. Others of the 

 muscle pieces, especially those stained for the nerve ending in 

 spindles, were fixed in a saturated aqueous solution of ammo- 

 nium picrate (Dogiel) ; cleared in equal parts of ammonium 

 picrate and glycerine and teased under the dissecting micro- 

 scope, and mounted in the picrate-glycerine mixture. In this 

 way, it was often possible to obtain very complex nerve end- 



