36 



XERYOUS SYSTEM AND GENEEAL SENSATION. 



i 



Fig. 16. A, single primary fibres from an intercos- 

 tal nerve of the common sparrow. B, several primary 

 fibres and ganglionic cells, from one of the thoracic 

 ganglions of the same bird. *A single ganglionic cell, 

 with a clear nucleus and darker nucleolus. 



I 



internally a clear ve- 

 sicular-looking nu- 

 cleus, which in its 

 turn mostly includes 

 a nucleolus. They 

 are composed of ex- 

 tremely fine mole- 

 cules, connected to- 

 gether by a semi- 

 fluid, glutinous, or 

 viscid, amorphous 

 substance. It is 

 doubtful whether or 

 not they possess a 

 delicate transparent 

 proper capsule. For 

 the major part, however, each gan- 

 glionic corpuscle is surrounded by 

 a cellulo-membranous capsule or 

 sheath : extremely delicate, greyish 

 or reddish coloured cellulo-mem- 

 branous fibres, furnished with nu- 

 clei, are interwoven into true cap- 

 sules ; but from these the ganglio- 

 nic corpuscles very readily become 

 detached and fall out. Frequently, 

 as, for instance, in the cervical por- 

 tion of the sympathetic nerve (fig. 

 17, A and B), this cellulo-mem- 

 branous sheath is so highly de- 

 veloped, that the gangliouic cor- 

 puscles (A, a, a) appear to be 

 bedded in a kind of matrix, which 

 is only intersected here and there 

 by single primary fibres (B, a, a) ; 

 these, like the corpuscles, seeming 

 to be separated and kept apart 

 by the abundant cellular tissue. 



Fig. 17. A, thin slice from the superior cervical ganglion of the calf; , gangli- 

 globules ; I, primitive fibre ; c, involucrum of the ganglionic cells. B, thin slice 

 trom the soft nerve of the plexus maximus carotidis of the calf; , a, a, isolated pri- 

 mary fibres ; b, b, thick sheaths of the same. After Valentin. 



