21 NERVOUS SYSTEM. 



when we come to study the structure and relations of these 

 small fibres, which seem in many instances to be simple 

 prolongations, without alteration, of the axis-cylinder of the 

 medullated fibres, it will be seen that they are chiefly found 

 in the peripheral terminations of the nerves and in the fila- 



FlG.l. 



Nerve-fibres from the human subject, magnified 350 diameters ; four small fibres, of which two 

 are varicose, one medium-sized fibre with borders of single contour, and four large fibres; of 

 the latter, two have a double contour, and two contain granular matter. (KOLLIKEK, Hand- 

 luch der Gewebelehre, Leipzig, 1867, S. 289.) 



ments of connection of the fibres with the cells. The study 

 of the fibres in these relations constitutes the most important 

 part, physiologically, of the anatomy of the nerves, and pre- 

 sents the greatest difficulties in the way of direct observa- 

 tion ; and, for that reason, we shall treat of these questions 

 separately, and defer until then the full consideration of the 

 non-medullated fibres. 



Gelatinous Nerve-Fibres (Fibres of It emetic). These 

 fibres are entirely different in their anatomy from either of 

 the varieties of fibres just considered. They are found chiefly 

 in the sympathetic system, and in that particular portion of 



