1881. ] The Brain of the Locust. 203 
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antennal lobes, and the commissures surrounding the cesophagus 
and connecting the brain with the subcesophageal ganglion, and 
which arise from the commissural lobes. Finally a “ mushroom 
body” is situated in the upper and central part of each hemi- 
The Central Body—tThis is the only single or unpaired organ 
in the brain. It is best seen in section 17°(Pl. u, Fig. 2), which 
also passes through the optic and antennal lobes and the trabeculz 
and mushroom bodies. This singular organ is apparently present 
in all winged insects, though differing somewhat in structure in ~ 
different insects. It is,as seen in Pl. u, Fig. 2, situated in the 
same plane as the peduncle and in the same plane as the center 
of the entire mushroom body, and rests upon the inner sides of 
the trabeculae. Section 16 does not pass through it, though the 
next section, which is ;}y inch thick, passes through its middle. 
Section 18 (Fig. 4) passes through its back, while the next section 
does not include any part of it; hence its antero-posterior diame- 
ter is slightly over 45 of an inch. It is about twice as broad as 
high, and thus is a small body, though from the universality of 
its occurrence in winged insects, it may be one of considerable 
importance. 
It is surrounded by a dense net-work of fibers containing a few 
small ganglionic cells, the fibers in front continuous with those 
near the bottom of the frontal median furrow and connecting the 
two optic lobes, Posteriorly the fibers apparently are not con- 
tinuous with those of the trabeculae; hence the central body 
appears to be quite isolated from the rest of the brain. Its sub- 
stance, when magnified 400 diameters, appears to be a white 
granular matter like the adjoining parts of the brain, It is divided 
into two parts, the superior and inferior, the former part constitu- 
ting the larger part of the body. The inferior portion is separated 
by fibers from the superior; it contains numerous nucleated 
spherical cells situated either irregularly or perhaps primarily (see 
Pl. rv, Fig. 3, of the pupa) in two rows when fewer in number 
than in the adult. The superior and larger division of the cen- 
tral body contains two series of what we may call waicellular bod- _ 
ies, sixteen in a series. The lower series are spherical or slightly 
elongated, and rest in the fibrous partition or septum, forming the 
floor of the superior division of the central body. The upper 
row of bodies are cylindrical, and about three or four times as 
