294 The Brain of the Lecust. [April, 
long as thick. They are separated by thin fibrous septa. PI. rv, 
Fig. 2, represents the central body enlarged 225 diameters. When 
we examine the central body in an earlier stage, z. ¢., the sec- 
ond pupal (PI. 1v, 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 commis- 
sural 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 
central body must be unlike that of an ordinary commissural lobe. 
Flogel states that the number of “sections,” or what I call uni- 
cellular bodies, is eight; we have counted sixteen. Both Flogel 
and Newton appear to regard these bodies as simply’spaces oF 
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'— 
“ Dujardin pointed out that in some insects there were to 3 be 
seen upon the upper part of the brain certain convoluted portions 
which he compared to the convolutions of the mammalian brain, 
and, inasmuch as they seemed to be more developed in those 
insects which are remarkable for their intelligence, such as ants, 
1Qn the Brain of the Cockroach. By E. T. Newton. Quart. Journ. Microscopi- 
cal Science, July, 1879, pp. 341, 342. 
