THE NERVOUS SYSTEM. 



NERVOUS TISSUE. 



NERVOUS tissue is of two kinds, gray or vesicular, 

 and white or fibrous. These two kinds of tissue, associ- 

 ated in varying amounts and positions, form the essential 



FIG. 115. NERVE-FIBRES. 



I. :i. mi'ilull.-itcil nerve- ti bre ; b, non-medullated nerve-fibre; 2, nun-medullated nerve- 

 fibre : 3, nerve-fibres witli Rauvier's nodes : 4, nerve-fibre treated with osmic aid : 5, nerve- 

 fibre showing axis-cylinder: (i, nerve-fibre showing n, neurilemma; v, medullary sheath ; 

 t, axis-cylinder. 



elements of the nervous system, which is divided into two 

 great systems, the cerebro-spinal and the sympathetic. 

 The cerebro-spinal axis is contained within the cranium 

 and spinal canal, and sends out a number of pairs of 

 nerves that bring the several parts of the body into close 

 connection with the central axis. The sympathetic sys- 

 (270) 



