Huber-DeWitt, Nerve-Endifigs in Muscles. 2 1 1 



tissue. In the tortoise, many of the muscle-spindles are com- 

 pound, showing more often two, occasionally three areas of 

 nerve distribution. One, two, or three large medullated nerve 

 fibers go to the smaller muscle-spindles, or to each area of nerve 

 distribution in the compound spindles. The spindle-nerves are 

 surrounded by a sheath of Henle, which (see Fig. 28 and 30) 

 becomes continuous with the capsule and with the axial sheath. 

 The spindle-nerves are medullated until they are within the axial 

 sheath, and also show the short internodal segments, mentioned 

 by Sherrington for mammalia, as previously quoted. Once 

 within the axial sheath, they soon lose their medullary sheath, 

 may now undergo further branching, and may be traced for 

 longer or shorter distances by the side of, or between the intra- 

 fusal fibers. The ultimate ending is on the intrafusal fibers, 

 outside of the sarcolemma, but within the connective tissue 

 sheath surrounding the intrafusal fiber. This may be seen 

 in Figs. 29 and 30. The configuration of the ultimate ending 

 of the non-meduUated end-branches of the spindle-nerves is 

 shown in Fig. 28, a portion of a compound muscle-spindle of 

 Emys meleagaris, stained in methylene blue and alum cochin- 

 eal. In this figure, the ending of the non-medullated fiber 

 (terminal branch of a spindle-nerve) designated by a, may be 

 regarded as typical. These endings are somewhat difficult to 

 describe and may perhaps be best understood by reference to 

 the figure. They may be likened to a strip of paper, which 

 has, from place to place, been cut nearly in two, the various pa- 

 per segments thus produced being further trimmed and scal- 

 loped into irregular, triangular, oval, or spindle-shaped forms, 

 which are connected by narrow uniting bridges; the whole ending, 

 as thus described, has a somewhat serpentine course on an in- 

 trafusal muscle fiber, the irregular, broader portions being 

 moulded to the side of the intrafusal fiber. Only one complete 

 ending is shown in the figure above referred to, and portions of 

 other endings ; this is inevitable in sections. 



In preparations of muscle-spindles stained in methylene 

 blue, fixed in ammonium picrate and teased, cleared and mount- 

 ed in glycerine-picrate, it may be seen that a spindle-nerve may 



