338 THE INTERMEDIATE PRIMATES 



tions. These reduplications appear mainly in the dorsal limb of the loop. 

 The fundus is relatively thick and the ventral branch of the nucleus is some- 

 what curved, with its concavity directed forward. The mesial extremity 

 points ahnost directly toward its fellow of the opposite side. The dorsal 

 branch of the loop is less extensive than the ventral branch, presenting the 

 reduplications already mentioned. The hilus of the nucleus is bridged over by 

 the dorsal accessory olivary nucleus. The whole olivary complex extends 

 upward to a point just below the lateral recess ot the iourth ventricle, where 

 it rapidly reaches its termination. 



The dorsal accessory olivary nucleus and the dorsal branch oi the mierior 

 olivary nucleus throughout their entire extent lie in relatively close contact 

 with the ventral surface of the reticular formation, out of which they seem to 

 differentiate. 



The Reticular Formation 



As reconstructed, the reticular formation appears as a flattened lamina 

 of gray matter applied to the lateral surface of the ventral gray 

 column. It extends dorsally and laterally to come into contact with the 

 substantia gelatinosa trigemini. It increases rapidly in bulk, pn^portion- 

 ally with the decrease in the ventral gray column which gradually 

 becomes absorbed by the expanding reticular formation. In the mid- 

 oblongatal region, the reticular formation forms a relatively massive struc- 

 ture, somewhat triangular in shape, its base being applied to the central 

 gray matter mesially, and to the base of the nucleus of the column of 

 Burdach laterally, while its apex extends between the inferior olivary com- 

 plex and the substantia gelatinosa trigemini. 



Continuing from this point upward, the reticular formation undergoes a 

 considerable reduction, due chiefly to the increasing development of the 

 inferior olivary nucleus, until the upper limit of this structure is 



