cxiv Journal of Comparative Neurology. 



The lateral cerebellar columns pursue a very simple course up to 

 the outer part of the cerebellar crus. 



The ventral columns are made up largely of the dorso-median 

 fasciculus. 



The second part presents detailed descriptions of the internal 

 origins of the cranial nerves. 



/. Hypoglossus . The first cervical nerve sends its fibres chiefly 

 to the ventral cornu of the same side, but that some fibres cross to 

 the opposite side in the ventral commissure is shown by degeneration 

 effects after section of the first cervical in the dove. Farther cephal- 

 ad the fibres of the hypoglossus take a similar course, the crossed 

 fibres entering the raphe. Recent methods of investigation have neg- 

 atived the tract formerly described as descending along the raphe from 

 the cerebrum. 



The cells of the nidulus of the hypoglossus are connected with 

 the higher centres by fine fibre tracts, which passing mesad enter the 

 ventral bundles. Only rarely could they be traced to the neighbor- 

 hood of the raphe and commissural fibres passing transversely through 

 the raphe between the two niduli could not be demonstrated. 



This relation was found chiefly in the gallinaceous birds and is 

 regarded as primitive, because here the resemblance is closer to a mo- 

 tor root of the cord. In most other birds there is also a second nidu- 

 lus for the hypoglossus, composed of large multipolar cells lying dors- 

 ad and cephalad of the first. When both niduli are present the 

 ventral is smaller in proportion as the dorsal is larger. Fibres of the 

 hypoglossus cannot be traced to the cephalic end of the dorsal nidu- 

 lus. This end lies beneath the dorsal vagus nidulus and appears to 

 serve also the ventral vagus root. No crossed fibres from the dorsal 

 niduli were observed. Both niduli correspond to cells of the ventral 

 cornu of the cord, and in all cases the hpyoglossus is to be compared 

 with the motor root of the spinal nerves. 



//. Vagus Group, (a) Accessorius. Emerging fibres of the 

 accessorius lie just dorsad of the dorsal cornu in the cervical region of 

 the cord, cephalad of the exit of the dorsal roots of the first cervical 

 nerve. They are directed mesad, then ventrad to a cell-cluster lying 

 at the base of the dorsal cornu near its lateral border. Scattered 

 cells apparently belonging to this cluster are found farther cephalad in 

 the medulla, though the nerve fibres cannot be followed to them. 

 Farther cephalad, these cells become more numerous and constitute 

 the ventral nidulus of the vagus, which, as above mentioned, is so 

 closely related to the dorsal nidulus of the hypoglossus. 



