370 OLIVER S. STRONG 
or end in either the pons or the masses of gray above mentioned. 
Some of them can be traced into the pons. Some of these bundles 
are shown in a higher magnification in figure 13. They would 
thus seem to be aberrant pontile fibers. Besides these bundles 
there are other bundles seen on the right side in the central gray 
which on the one hand pass dorsally along the side of the ventricle 
(fig. 12) and on the other hand, at a higher level (fig. 14), pass 
ventrally into the right reticular formation. Where this occurs 
there are streaks of gray, also containing nerve-cells of normal 
appearance, in the reticular formation (fig. 14) with which they 
appear to be connected. Some of these bundles, at least, pass 
into the pons laterally to the medial fillet. It hardly seems 
possible that any of these bundles could represent aberrant striae 
medullares and they must be looked upon as abnormal. Other 
similar peculiar bundles connected with the central gray at higher 
levels will be noted below. 
No definite indications were noted of an asymmetry in the 
perpendicular pontile fibers nor of the various tegmental nuclei 
(nucleus centralis superior, etc.) except the nucleus ruber. 
The left central tegmental tract is very well developed and 
conspicuous while the right one is completely or nearly completely 
absent. | 
Sections through the isthmus (figs. 15, 16 and 17) show strik- 
ingly the above inequalities in the pons and in the central teg- 
mental tracts. The right superior cerebellar peduncle is fully 
or even over normal size while the left is represented by a few 
small bundles hardly apparent in the figures, but representing 
apparently dorsal, middle and ventral parts of the peduncle. 
It is interesting to note here again how these inequalities in large 
bundles of fibers entail asymmetrical arrangements of other 
structures themselves normal. In figure 15 the left lateral 
fillet has assumed its dorsal position along the side of the teg- 
mentum while the right is still close to the pons. The asym- 
metry of the medial fillet is also largely due to the fact that the 
left fillet has passed further laterally than the right. While 
these appearances may be due partly to obliquity of the section, 
they must be regarded as largely due to the adjustment required 
