OF DEXISOX UNIVERSITY. 



55 



occupying the whole ventral cornu and middle gray portion. (Plate 

 XIII,, Fig. 4, d.) 



Passing cephalad into the medulla, in a cross section taken just 

 caudad to the decussation of the motor tracts (Plate XIV, Fig. i,) the 

 general arrangement of the gray and white matter is quite similar to 

 that of the cord in the cervical region. The columns of Goll are very 

 much reduced in size, being compressed, as it were, by the decussa- 

 tion of the motor fibres and, a little further cephalad, form the/«///r- 

 tdus gracilis. 



The dorsal caput cornu is much enlarged and the gray matter 

 extends laterally almost to the surface. The gray matter is everywhere 

 filled with cells of the multipolar type, which are scattered almost uni- 

 formly through the substantia gelatinosa and the dorsal cornu especially 

 is charged with nutritive corpuscles. This uniform distribution of cells 

 through the gray matter seems to accompany the reduction in the num- 

 ber included in the various nuclei. The nucleus of the ventral cornu 

 (Plate XIV, Fig. i, b,) is still quite manifest, but the second group, 

 which lies somewhat lateral to the first, has lost its identity in the gen- 

 eral distribution of cells. 



The number of cells present in the median nucleus (Plate XIV, 

 Fig. I, d,) seems to be also somewhat reduced. The cells which were 

 so conspicuous in the neck of the dorsal cornu, (Plate XIII, Fig. 4, 

 a,) are also much scattered, while a remnant of them seems to persist 

 though crowded more dorsally, (Plate XIV, Fig. i, r.) We notice also 

 the accumulation of a few cells, somewhat e.xternal and lateral to the 

 nucleus of the ventral cornu which is the beginning of a large ventro- 

 lateral nucleus extending cephalad, (Plate XIV, Fig. 1, e. Fig. 5, r.) 



The expansion of the gray matter seems to be due to the insertion .^^ 

 of a large number of nerve bundles which are distributed through the 

 gray matter and run longitudinally in the medulla, beginning the for- 

 matio reticularis of the medulla a little further cephalad. In the sec- 

 tion under consideration there is also shown the exit of a small bundle 

 given off to the eleventh nerve root, (Plate XIV, Fig. i, <7.) The fibres 

 seem to be derived from the generally distributed cells. 



Passing a litde more cephalad in a section taken at about the first 

 fourth of the decussation, (Plate XIV, Fig 5,) we find that the nucleus 

 of the ventral cornu has entirely di.sappeared, while the ventro lateral 

 nucleus {Fig. 5, c,) is much enlarged and is composed of cells of the 

 multipolar type, measuring from .03 to .05 mm. in diameter (Plate 



