GELATINOUS NEEVE-FIBKES. 



429 



Fig. 276. 





period of their development, precisely in the condition of these 

 fibres of the sympathetic. Finally, it is even* true that the same 

 fibre in the adult is often seen to assume all possible varieties of size 

 in different portions of its course. 



There are, therefore, no nerve-fibres peculiar to the sympathetic 

 nerves; there being only the fine and the large fibres already de- 

 scribed as existing in the cerebro-spinal system. 



How, then, may we dispose of still other fibres found more espe- 

 cially in the peripheral branches of the ganglionic (sympathetic) 

 nerves the "gelatinous fibres," or "fibres of Eemak?" These, 

 when isolated, present the aspect of flat, pale fibres, 5 oV<y to 75^0 of 

 an inch wide, and ^Q^QQ f an i ncn thick, of an indistinctly striated, 

 granular, or more homogeneous substance. In these, acetic acid 

 shows elongated or fusiform nuclei, averaging about <y -J nTi of an 

 inch in length, and 75 1 oir f an i ncn in width. (Fig. 

 276.) They are found in great abundance in the 

 nerves of the impregnated uterus (Remak], some- 

 times amounting to from three to ten times the num- 

 ber of the dark-bordered true nerve-fibres. 



With Valentin, Kolliker, Bidder, and Yolkmann, 

 we regard the fibres just described merely as a form 

 of elastic tissue, or nuclear fibres. , For, ls, they ap- 

 pear to arise from the wall of the nerve-cells of the 

 sympathetic ganglia; Idly, they also exist in the 

 finest twigs of the spinal nerves, but, being absent 

 in the trunks, must be otherwise than nerve-fibres ; 

 3c%, their quantity always diminishes towards the 

 finest ramifications, which could not be the case 

 were they true nerve-fibres. This question cannot, 

 however, be settled in young animals; though in 

 them a nucleated fibre is not to be regarded as a 

 nerve-fibre, unless it can be traced into a dark -bor- 

 dered nerve-fibre, or to a process of a nerve-cell. 



Finally, the fibres of Eemak occur also in the ganglia on the main 

 sympathetic trunk ; but they do not extend much beyond them, 

 and therefore few are contained in the trunk of the nerve itself. 



Distribution of the Nerve- Fibres. 



The nerve-fibres constitute the principal part of all the nerves, 

 both cerebro-spinal and ganglionic. They also constitute most of 



Gelatinous fibres 

 (fibres of Remak) 

 from the solar plex- 

 us ; treated with a- 

 cetic acid to exhibit 

 thfir cell-nuclei. 

 (Magnified 320 dia- 

 meters.) 



