138 



NERVOUS TISSUE. 



from the insertion of the first, and makes several turns on the surface 

 of the cell, but within its capsule, which ai'e continued as spiral coils 

 round the straight fibre, and then the two part company, and appa- 

 rently run in opposite directions in the nervous bundle in which they 

 mingle. 



The spiral fibre bears large oblong nuclei along its course. These 

 are seen on its spiral turns upon the surface of the cell, and some, at 

 the commencement of the fibre, seem to be beneath the surface. It 

 may be single from the first, or begin by two or more filaments which 

 join at some distance from the cell. Both fibres increase iu size as 



Fk. 94. 



Pi-. ^0. 



Fig. 94. — Ganglion-Cell of a Prog, Magnified ; according to Be ale. 

 Eeduced and adapted from one of his figiires. a, a, straight tibre ; b, I, coiled fibre ; 

 c, smaller one joining it. 



Fig. 95. — Magnified Ganglion-Cell, from the Sympathetic of the Frog, according 

 TO J. Arnold. Yirch. Arch. 1SG5. 

 «, straight fibre ; h, coiled fibre, arising by a superficial net connected with nucleolus 

 of the cell ; c, c, capsule with nuclei. 



they proceed. They have at first the character of pale fibres (or axis- 

 cylinders), then one of them — generally the straight one, but it may be 

 the other— at a short distance from the cell acquires a medullary sheath 

 and l)ecomes a dark bordered fibre. At the same time it cannot be 

 positively said that l)oth fibres may not become dark bordered, or both 

 continue as pale fibres. The spiral fibres may make more or fewer 



