THE BRAIN OF THE LOCUST. 
237 
stage shows, in place of the calices, lour symmetrically situated balls of 
much smaller size ; the central body was very flat, and the other parts 
were wanting. In the pupa all the parts had attained their definite 
shape. It appears from his observations that the calices are the last to 
be developed. 
He then gives the results of his examination of the brain of caterpil- 
lars, as compared with that of the adult sphinx moth. In a caterpillar 
examined near the time of pupation, the central body is very much un- 
developed, forming a small linear transverse body (Querleiste), while the 
different parts of the mushroom body are indicated. In smaller cater- 
pillars it is scarcely possible to work out the development of the brain. 
In that of Pontia brassicce the mushroom body and central body were 
undeveloped, while in that of an Euprepia larva the double stalk of 
the mushroom body was developed as well as roundish calyx masses. 
But in a Xoctuid larva the entire mushroom body, including well-devel- 
oped trabecules and a very flat central body, was present. 
The brain of the mature pupae of Lepidoptera, for example Satumia 
carpini, contains all the portions of the adult brain, and in the same 
relative proportions. But a brain of Sphinx ligustri, in a considerably 
younger stage of development, did not differ much from the brain of the 
larva. 
We offer the following observations on the brain of the embryo locust, 
shortly before hatching, with much diffidence, as we are liable to be cor- 
rected by future observations in the same directions. The embryos 
were taken from the egg-shell, hardened in the usual manner, and then 
cut by Mr. Mason, the sections being frontal, the entire insect being 
embedded in a mixture of paraffine, wax, and oil. 
In the youngest stage (which we will call stage A) observed, the body 
and appendages were formed and the eyes with their facets, the pigment 
mass coloring the cornea pale reddish. 
At this stage, as seen in section 7 (PI. XII, Fig. 1), the antennal and 
optic lobes of the brain are indicated, but the central body and mush- 
room bodies are not yet differentiated. In a plane lying in front of the 
optic and antennal lobes, the brain is divided in each hemisphere into two 
regions or lobes, i. e., an upper (Figs. 1 and 8, up I) and lower cerebral lobe 
(low I). From these embryonic cerebral lobes are eventually developed 
the central body and the two mushroom bodies. The stratum of cortical 
ganglionic cells is, at this period, quite distinct from the paler unstained 
granular braiu matter. PI. XII, Fig. 1 a, represents the structure of the 
ganglionic cell-portion, which gradually passes into the central white brain 
substance, which is composed of fine granules or nuclei alone, and which 
do not apparently differ from the granules scattered among the ganglion 
cells. It is to be observed that there are no fibers among the granules. 
It thus appears that the brain of insects, like the other ganglia, origi- 
nally consists of a paler portion formed of fine clear granules (nuclei?), 
enveloped by a thick irregular layer of nucleated cells, containing fine 
granules outside of the nucleus. 
