THE BRAIN OF THE LOCUST. 
231 
of the pupa), in two rows when fewer in number than in the adult. The 
superior and larger division of the central body contains the series of 
what we may call unicellular bodies, sixteen in a series. The lower se- 
ries 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 long as thick. They are separated by thin fibrous septa. PI. XIV, 
Fig. 2, represents the central body enlarged 225 diameters. When we 
examine the central body in an earlier stage, i. e., the second pupal 
(PI. XIV, Fig. 3), we see that the body is covered above by a stratum of 
nucleated ganglion cells continuous with those next to the bottom of 
the upper furrow ; and that the fibrous septum between the upper and 
lower division also contains small cells. These cells disappear in the 
adult, and evidently give rise to the fibers which take their place. It 
will also be seen that the "unicellular bodies" are shorter, more cell- 
like, than in the adult; hence they seem to be modified ganglion 
cells, which have at an early date lost their nucleus and nucleolus. My 
observations on the central body of the locust agree in the main with 
those of Newton (compare his Fig. 9). His drawings are not especially 
clear and definite, but the differences appear to be unimportant. There 
are perhaps two (16, instead of " 12 or 14") more cellular bodies in the 
locust than in the cockroach. Unfortunately my sections of the brain of 
the cockroach do not show the central body. Dietl states that the central 
body is a " median commissural system." This description we would 
accept in a modified sense. We have shown that the unicellular bodies 
and the cells beneath them were once like the ganglion cells, but that 
they have lost their nuclei and nucleoli ; hence the functions of the cen- 
tral body must be unlike that of an ordinary commissural lobe. Flogel 
states that the number of "sections," or what I call unicellular bodies, 
is eight; we have counted sixteen. Both Flogel and Newton appear 
to regard these bodies as simply spaces or sections between fibrous 
partitions ; but it would appear that these sections are really modified 
cells, and that the fibrous septa, are possibly the cell-walls, somewhat 
modified. 
The mushroom bodies. — These curious organs have attracted a good 
deal of attention from writers on the brain of insects. Dujardin, in 1850, 
first drew attention to them. His memoir we have not at hand to refer 
to, but as stated by Newton 328 — 
Dujardin pointed out that in some insects there were to he seen upon the upper 
part of the hrain certain convoluted portions which he compared to the convolutions 
of the mammalian hrain, and, inasmuch as they seemed to he more developed in those 
insects which are remarkable for their intelligence, such as ants, bees, wasps, &c, he 
seemed to think the intelligence of insects stood in direct relationship to the devel- 
opment of these bodies. The form of these structures is described by the same au- 
thor as being, when fully developed, as in the bee, like a pair of disks upon each side, 
s^On the Brain of the Cockroach. By E. T. Newton. Quart. Journ. Microscopical Science, July, 
1879, H, pp. 341,342. 
