OF DENISON UNIVERSITY. 
57 
1 5) the fibres of the twelfth enter on the ventral surface just lat- 
eral to the pyramids, pass through the olivary body, which attains 
its maximum development at this point, and then through the formatio 
reticularis to its nucleus, on the floor of the fourth ventricle. The 
cells of this nucleus are of the multipolar type, measuring from .05 to 
.06 mm. in length, having nuclei about .01 mm. in diameter, with 
nucleoli. The axis cylinder process generally passes into a bundle of 
fibres leading to theTOOt of the nerve. I^ig. 5, Plate XV, presents a 
magnified view of the entire nucleus as it appears at this point. Just 
laterad to this is situated the nucleus of the tenth nerve Plate XV, 
I, a, and a magnified portion of the same J^ig. 2, of the same 
plate. The cells of this nucleus are somewhat smaller than those of 
the twelfth, though of about the same number and form. Just laterad 
to this nucleus is a large cluster of small cells which is evidently very 
closely associated with it. 
Still laterad we find a large group of cells which may be divided 
into two nuclei. The lateral one, (Plate XV, J^ig. i, c,) consti- 
tuting thQ cim eat e nucleus, contains cells measuring about .03 mm., 
imbedded in a very dense neuroglia (Plate XV, jFig. 6,) while the cells 
of the median portion are very much smaller and are more numerous, 
constituting the davate nucleus. 
The formatio reticularis is very largely developed and rather abun- 
dantly provided with cells which are of the multipolar type, measur- 
ing about . 04 mm. aud sending their processes in the general direc- 
tions of the fibres in which they are imbedded. Plate XIV, Fig. 4, 
will serve to illustrate their manner of distribution between the longi- 
tudinal fasciculi of the reticular formation. 
There is a marked decussation of fibres in the lower portion of 
the raphe in which are found multipolar cells of about .02-. 03 mm., 
which here form a considerable nucleus, (Plate XV, Fig. i, e, and a 
magnified view of the same, Fig. 3, of the same plate.) The decus- 
sation is of fibres from the olives, while large bundles appear to pass 
through the olives and thus around into the i'estifor 7 n tracts. A small 
lateral nucleus is also present. 
As we pass cephalad, in a section at the level of the entrance of 
the tenth nerve root, (Plate XVI, Fig. i,) we find the nucleus of the 
twelfth nerve, c, still represented on the floor of the ventricle and the 
nucleus of the tenth, very closely associated with it. The olives 
are much reduced in size, the nucleus of the raphe in the decussation 
