62 
BULLETIN OF THE LABORATORIES 
ences between any known sensory cells and those in question are cer- 
tainly as striking as their resemblance. 
Similar cells have been described by Belonci, in birds, Stieda in 
the turtle, and Herrick, in the alligator. As a matter of fact, no sub- 
stantial basis exists for determining the function of these cells. Their 
similarity to Purkinje’s cells of the cerebellum gives some force to the 
suggestion that there may be similarity in function if not in origin, 
though the resemblance is still greater to the cells of the ganglion of 
Gasser. 
These bladder cells are especially well seen in the horizontal sec- 
tions passing through the nuclei of the third and fourth cranial nerves. 
(Plate XIX, Fig. 2, Be. Be', Fig. 4, b.) 
These cells are .05-. 07 mm, in diameter and of a baloon or flask 
shape or polyhedral. The processes are few. and abrupt, and give rise 
to a very large fibre. Such cells are first encountered in the base of 
the tectum opticum, near the highest part of the nates and are sparsely 
scattered in the tract which passes in a gentle curve lat^rad and caudad 
and at the same time, somewhat ventrad, to form a disperse tract about 
the aqueduct and thence caudad to the anterior part of the fourth 
ventricle. Here the cells are most numerous and lie peripheral to the 
strong motor nucleus of the fifth, which lies near the ventricle. Al- 
though the two sorts of cells commingle in places, there is never any 
difficulty in distinguishing them. The general relation is always that 
described. The tract can be traced laterad and ventrad and the nu- 
cleus itself describes a strong lateral curve at the point of departure of 
the root tract, while scattered cells of this type can be traced to the 
point where the fibres are lost in the common root of the fifth. 
Moto 7 ' niielei of the trigeminus. The cephalad portion of the tri- 
geminal motor system is quite complicated. The highest recognizable 
portion is the elongate cluster bordering the caudad portion of the 
aqueduct and the cephalad part of the fourth ventricle. The cells are 
figured, (Plate XIX, Fig. 4, a,) and are of the usual motor type, 
measuring .05-. 06 mm. in length, by .02-.025 mm. in width. The 
prevailing direction of the principal processes is caudad, i. e. toward 
the root, the opposite extremity being multipolar. 
A second nucleus lies ventro laterad from this one and appears in 
horizontal sections through the highest portion of the root of the fifth. 
It lies nearly opposite the caudad part of the pre pedunculus cerebelli 
and is of circular outline and about fifty cells lie in one horizontal 
