[May 1, 



figures will serve better than a long description to give a correct 

 idea of their terminations. Whilst fig. 2, drawn under a low mag- 

 nifying power, represents their general mode of distribution, fig. 3 

 shows a small part of their ramification and two or three termina- 

 tions, highly magnified. It will be seen that the larger fibres 

 divide and redivide into smaller branches, which still retain their 

 dark contours, but give off in their course lateral pale branches, and 

 finally end in pale and numerous prolongations. In the pale fibres, 

 at their commencement the membranous sheath is distinct from the 

 contained fibre, which doubtless consists of the axis-cylinder, with at 

 first some part of the medullary substance ; in their progress the 

 sheath becomes blended with the contents, and can no longer be 

 distinguished as a separate structure. Nuclei (/,/, fig. 3) are seen 



Fig. 3*. 



all along the pale fibres, and also on the smaller dark fibres. In 

 short, the structural character of the pale sentient fibres is, so far as 

 it can be discovered, essentially the same as the pale terminations of 



* Fig. 3. Part of ramifications of the sentient fibres of the cutaneous muscle, 

 as seen with Hartnach's Objective No. 7, and Eyepiece No. 1. a, a, Dark-bordered 

 fibres with fine sheath and nuclei; b,b,b, pale fibres still having a sheath arid 

 pale contents (axis-cylinder) ; c, division of the axis-cylinder of one of these 

 fibres ; d, d, d, non-medullated terminal fibres, with nuclei /, but on which no 

 sheath can be recognized. 





