264 DETAILED SYNTHESIS. 



605. THE SPINAL NERVES MAY BE DIVIDED into two 

 classes : 1st, those that have their origin or inner extrem- 

 ities in the spinal cord, where they connect with the 

 ganglionic cells of the cord; and 2d, those that ex- 

 tend up through the spinal cord to the Brain, and which 

 are truly Cranial nerves. 



606. Inf. The SPINAL COED is partly a nerve, or bundle of nerves, 

 and partly constructed of nervous centres or ganglia. 



607. THE CRANIAL NERVES, including the latter 

 division of the spinal, are divisible into two classes, the 

 Motor and the Sensatory. 



608. THE MOTORY AND SENSATORY NERVES are alike 

 except that on the latter, quite close to their origin, 

 there is a ganglion, the use of which is not understood. 



609. IT is ALSO OBSERVABLE that the Motor nerves 

 are connected with the front part of the spinal cord and 

 the Sensatory with the back part. (See Figs. 76 and 69.) 



610. ALL THE SPINAL NERVES have two roots or ori- 

 gins, and some fibres of both commence in the cord, and 

 some of both extend to the Brain. Some of the nerve- 

 fibres commence from the cells of the ganglia on the 

 roots of the sensatory nerves. 



611. SOME OF THE CRANIAL NERVES proper have 

 two roots, but most of them but one, and those are 

 either all motory or all sensatory. 



612. At their outer extremities SOME OF THE NERVES 

 lose their external sheath and TERMINATE by their axis- 

 part on the sheaths of the muscular fibrillse. 



613. NERVES ALSO TERMINATE in three peculiar 

 bodies or corpuscles. 



614. THE PACINIAN BODIES are composed of a num- 

 ber of layers of sinewy tissue, the spaces between which 

 are filled with a colorless liquid. The axis only of the 

 nerve extends along the centre. The use or mode of ac- 

 tion is unknown. 



605. How ? 606. What said of-? 607. Class. 60S. Compare -. 609 What-? 

 610. What true of ? 611.What said of roots of ? 612. How do-? 614.Whatare-? 



