MEDULLA OBLONGATA OF AMBLYSTOMA 



427 



Fig. 57 Diagram of the connections of tlie mesencephalic root of the trigeminus 

 in Lirval Amblystoma. The outline of the sketch is taken from the dorsal view 

 of the model of a 38 mm. larva shown in figure 1. The individual fibers of the root 

 arise from cells of the nucleus magnocellularis tecti {nuc.tnes.V.), those from the 

 caudal part of the tectum in part decussating in the commissura veli in company 

 with the IV nerve and the cerebellar commissure. The root then descends in 

 several strands through the body of the cerebellum and along the rostral and lateral 

 border of the motor V nucleus. Laterally of this nucleus many of the fibers of 

 this root divide into two branches each of which is as thick as the parent stem. 

 One of these branches is directed backward and inward to end by free arborizations 

 in the motor VII nucleus; the other enters the peripheral root of the V nerve. 

 Other finer collateral branches of the root fibers enter the motor V nucleus. 



