UNILATERAL CEREBELLAR AGENESIA 363 
truded much more on the left side, indicating a greater develop- 
ment of the nuclei pontis and longitudinal pontile fibers on that 
side (fig. 1). The left crusta was wider than the right. 
A dorsal view of the brain stem, the cerebellum removed (fig. 5) 
showed the following: The median line showed here, as well 
as on the ventral view, a marked curvature with the convexity 
toward the left. This may have been due to the position in 
which the brain, with the cord attached, rested in the jar of 
formalin but the fact that the brain was well hardened in situ 
by injections of formalin rendered this less probable. 
The left clava was more elongated, extending further cephalad 
than the right and was also narrower. The same was true of 
the left cuneus. In the floor of the fourth ventricle, the left 
ala cinerea extended much (nearly 2 mm.) further cephalad than 
that on the right. The two trigona hypoglossi were nearly 
symmetrical; the left eminentia teres was further cephalad than 
the right. The left trigonum acustici was also further cephalad 
than the right and appeared to be somewhat less prominent 
(fig. 5). It would seem that this asymmetry of these structures 
is attributable in part or in whole to the unequal pressure exerted 
upon the medulla during its growth by the unequally developed 
halves of the cerebellum. The fact that the left clava and cun- 
eus is longer and narrower than the right produces an inequality 
in size of these structures in transverse sections which might 
be wrongly attributed to an inequality of development, but is 
really only a difference of shape. 
The left corpus restiforme was much smaller than the right. 
The funiculus separans (Retzius) and area plumiformis (Retzius) 
were present on each side. The striae acusticae were not visible. 
The sides and roof of the fourth ventricle exhibited asymmetrical 
markings. 
The right superior peduncle was much larger than the left. 
The taeniae pontis were present on both sides but much more 
prominent on the left, the accessory bundle from the groove 
between the lingula and velum noted by Retzius (das Men- 
schenhirn, p. 49) being observed. 
