Huber-DeWitt, Nerve-Endings in Muscles. 209 



in the few instances seen by us, enter by opposite poles. In 

 Fig. 37, may be seen such a muscle-spindle receiving two 

 nerve fibers ; these, as may be seen, approach the spindle in 

 two quite distinct nerve trunks. (In the figure, only the intra- 

 fusal muscle fibers and the nerve fibers are shown. The sketch 

 is from a methylene blue preparation, fixed in ammonium pic- 

 rate and cleared in glycerine-picrate. In the preparation, the 

 fibrous capsule, as also the fibrous connective tissue sheath 

 around the nerve fibers continuous with the capsule, could be 

 made out, although not very distinctly; also the fact that in the 

 portion of the intrafusal fibre not distinctly striated in the fig- 

 ure, there were about 10 or 12 nuclei. It was, however, found 

 that if all these structures were reproduced in one figure, the 

 ultimate ending of the nerve fibers, which we hope here to 

 show more especially, would come out indistinctly by reason of 

 the fact that it would be covered up by nuclei, etc.) The 

 meduUated spindle-nerves lose their medullary sheaths soon after 

 entering the capsule ; the ultimate endings are therefore non- 

 medullated, and are, we believe, under the axial sheath in con- 

 tact with the intrafusal fiber. We have not been able to make 

 longitudinal or cross sections of the muscle-spindles of the 

 snake; the number, of successfully stained endings was not suf- 

 ficient to admit of this. Yet in optical sections of the spindles, 

 a connective tissue sheath, inside of the capsule, which we re- 

 garded as the axial sheath, seemed to be outside of the ultimate 

 ending of the nerve fibers. 



The ultimate ending of the spindle-nerve is as follows : 

 The non-medullated continuation of the spindle-nerve di- 

 vides, soon after its entrance, into two or three branches ; these 

 branches may be traced on the intrafusal muscle fiber for some 

 distance, giving off in their course band-like offshoots, which 

 may partly enclasp the intrafusal fiber {a, Fig. 36), or almost 

 completely encircle the intrafusal fiber {b, of the same figure) ; 

 the fiber itself ending in one or two large disc-like expansions, 

 c, of the figure. The non-medullated fiber, before giving off 

 the band-like offshoots above mentioned, may present one, 

 two, or three flattened expansions, of round, oval, or spindle 



