Kingsbury, Brain of NccUinis. lyy 



have physiologic connection, might be the nidus of origin of 

 some intra-cerebral tract or tracts, &c. 



In Ncctiiriis, the cranial nerves generally found in Amphibia 

 are present. The difficulties in the recognition of the eleventh 

 and twelfth nerves have already been spoken of. The two 

 motor roots rising from the ventral columns caudad of the tenth 

 (X") have been termed the 1st and 2nd spinal nerves, despite 

 the fact that they have no dorsal roots or ganglia.^ Their 

 mode of origin within the brain is that shown by Stieda for the 

 motor roots of the spinal nerves in the Axolotl ; some of 

 the fibers pass directly dorsad to the ventral horns, a larger num- 

 ber turn cephalad in the ventral tracts, others caudad. No 

 special nidus or origin for either of the nerves was recog- 

 nized. 



Vagits. — This nerve and the glossopharyngeal are closely 

 related to each other. The vagus arises by two roots which 

 are formed in NLXtunis of seven minor rootlets, of which the 

 two caudal unite to form one root, the eleventh of some writers, 

 the cephalic five forming the tenth. X', the largest, arises 

 from the lateral aspect of the oblongata and derives its fibers 

 from two sources,^ (i) \\\q fasciculus coimnunis, whose fibers 

 leave the brain the more dorsally, (2) ascending fibers, chiefly 

 of large caliber, which migrate ventrad into the ascending V. 

 Some of these fibers may be traced caudad as far as the exit of 

 the 2nd spinal nerve. Burckhardt has found in Protoptcnis a 

 decussation of similar ascending fibers of the tenth caudad of 

 the metatela. In Ncctiwiis a decussation of small fibers was ob- 

 served in this region but their relation to the tenth nerve could 

 not be determined. Strong speaks of this component in the 

 tadpole as derived from the ascending V. In Nectiinis they 



1 Even in man, Gray (Anatomy, Descriptive and Surgical) states that the 

 dorsal root of the first spinal nerve is much smaller than the others and fre- 

 quently has no ganglion. 



^ The true physiologic direction of the fibers is for convenience of descrip- 

 tion disregarded here, thus though really the impulse is " descending," the 

 old term, ascending V is retained. 



