MACROMYELON OF MAMMALIA. 



87 



lateral column are marked p, those continued over the olives, w, 

 and those over the prepyramids, v ; they form the trapezium in 

 lower Mammals. 



The nucleus in the trapezium, on each side of the raphe, so 

 closely resembles, at a higher section, the olivary body, that it has 



Transverse section of the macromyelon through the lower third of the olivary bodies. 

 Magnified ten diameters. 



been termed the ' upper olive ' ; it makes its appearance near 

 where the lower olives first diminish in size. In the Sheep it 

 appears as a group of large stellate multipolar cells, and these 

 cells are more numerous in the Rodents, and still more so in the 

 Cat. In the Rabbit the upper olivary body is convoluted in three 

 or four turns ; in the Mouse it consists of a wavy mass of large 

 and numerous cells ; its structure is especially distinct in the Cat. 

 The f post-pyramidal ' and 'restiform' nuclei are present in 

 all Mammals. The olivary bodies consist of layers of small cells 

 penetrated by the arciform filaments, by which they are connected 

 Math each other and with the raphe ; they are not absent in the 

 Sheep. The transverse section of the human medulla oblongata 

 in the region of the first cervical nerve is more circular, less 



