290 The Brain of the Locust. [ April, 
the center of the ganglion and mingling with the fibers forming 
it. Hence, in all probability the fibrous mass of the central part 
of the brain mostly originates from the peripheral or cortical gan- 
glion cells. 
To briefly describe the brain of the locust, it isa modified gan- 
glion, but structurally entirely different from and far more com- 
plicated than the other ganglia of the nervous system. It 
possesses a “central body,” and in each hemisphere a “ mush- 
room body,” optic lobe, and optic ganglion, and olfactory lobe, 
with their connecting and commissural nerve fibers, not found in 
the other ganglia. Inthe succeeding ganglia the lobes are, in 
general, motor; the fibers composing the cesophageal commis- 
sures, and which arise from the cesophageal commissural lobes, 
extend not only to the subcesophageal ganglion, but pass along 
through the succeeding ganglia to the last pair of abdominal 
nerve centers.) Since, then, there is a direct continuity in the 
fibers forming the two main longitudinal commissures of the 
nervous cord, and which originate in the brain, it seems to follow 
that the movements of the body are in large part directed or co- 
_Ordinated by the brain? Still, however, a second brain, so to 
1 We have seen that the two great longitudinal commissures pass directly from the 
the brain into and then pass backward from the subcesophageal ganglion, but beyond 
that point we have not traced their course, as it is generally supposed that they extend 
pmpanpayr: to the last abdominal ganglia, This has indeed been shown to. be 
y Michels, in his admirable treatise on the nervous system of a beetle 
pa: in Siebold and Kdlliker’s Zeitschrift fiir wissen. Zoologie, Band 34, Heft. 
4, 1880. Michels states that each commissure is formed of three parallel bundles 
of elementary nerve fibers, which pass continuously from one end of the ventral or 
ervous cord to the other. ‘‘ The commissures take their origin neither out of a cen- 
ei sep (or paanieigen tens nor from the peripheral ganglion cells of the 
several ganglia, but are es tions of the longitudinal fibers which decrease 
ane in thickness, and roe anteriorly through the commissures forming the 
cesophageal ring to the brain,’ 
2 The following extract from Newton’s paper shows, however, that the infra or 
subcesophageal ganglion, according to Faivre, has the power of codrdinating the 
movements of the body;. still it seems to us that the brain may be primarily con- 
cerned in the exercise of this power, as the nerves from the subcesophageal ganglion 
ee only the mouth ee “ The physiological experiments of Faivre, in 1857 
nn. J. Sci. Nat., Tom. viii. p. 245), upon the brain of Dytiscus in relation to loco- 
cine are of very ssn interest, showing, as they appear to do, that the 
power of codrdinating the movements of the body is lodged in the infracesophageal 
ganglion. And such being the case, both the upper and lower pairs of ganglia 
ought to be regarded as forming sp of the insect’s brain.” Quart. Jour. Micr. 
Sc., 1879, p. 342. 
