INTERLACEMENT OF THE CEREBELLAR PEDUNCLES. 4G9 



medulla it contains, in strong relief as a dark area when com- 

 pared with the white substance of the columns. 



The anterior investment of the posterior horn (posterior part 

 of the lateral column) originates in a germ mass, identical with 

 that of the posterior column of the spinal cord, and may be, 

 physiologically speaking, included amongst the centripetal 

 tracts. In the formation of this region, presenting characters 

 that are uniform with the posterior column, perhaps only 

 those fasciculi of the pes of the fillet take part that have pro- 

 ceeded through the tract of the valve of Vieussens from the 

 cerebellum (page 459). 



In this case the whole of that portion of origin of the fillet 

 layer that, proceeding from the corpora quadrigemina, extends 

 into the spinal cord, would belong to the centrifugal tracts. 



Internally to the pes of the loop, and posterior to the layers of 

 the fillet, which leave room for it by a slight convexity of their 

 contour, is found the superior olivary body of Schroder v. d. 

 Kolk (figs. 253, 254, 255, 256, 0), described by Stilling in the 

 brain of Man as an accessory mass of his inferior trigeminal 

 nucleus, but correctly described and named, also in Man, by 

 Deiters. It extends from the uppermost roots of the facial to 

 the lower border of the pons in Man, and in animals to the 

 corpus trapezoides. In the brain of Cercocebus cinomolgus 

 I found it to be two millimeters and a half in length. In 

 Man its outline is insensibly blended with the adjoining 

 parts ; it exhibits in animals, as, for instance, in the Dog, a 

 well-defined contour composed of a sinuous U-shaped external 

 principal mass, and when seen in transverse section an elon- 

 gated, oval, internal superior accessory olivary body. From 

 a longitudinal section of the brain of the Monkey, beautifully 

 made by Dr. Clason, Prosector in Upsala, I am convinced 

 that the superior olivary body is traversed by fasciculi of 

 the continuation of the tegmentum in the posterior division 

 of the pons, which are connected with its slender (30 /u long 

 and 6 9 /i broad) cells, and, as seen in the mosaic presented 

 on transverse section, are found behind the layer of the fillet 

 and internal to the pes of the fillet. 



The inferior olivary body belonging to the superior half of 

 the medulla oblongata obtains in Man, by the extension and 



