1898.] “ Mushroom Bodies” of the Hexapod Brain. 645 
optera makes the same observations as to the differences in the 
same species, while Berger (’78) considered the structures as 
“ organs of projection of the first order.” 
The supposition of Dujardin obtained its best support so 
far as the older methods would avail in the comprehensive 
work of Flégel (78) covering the whole group of hexapods: 
Here, one may see at a glance that the development of the 
structures largely coincides with the development of intelii- 
gence, as shown by the following abridgement of his table: 
A. The four cups completely developed. 
1. Very highly developed, Vespa. 
{ Apis, Formica Pompi- 
\ lus, Ichnewmonide. 
3. Without rim, Blatta. 
4. Very small, Cossus, Sphinx, Vanessa. 
B. Cups incomplete. 
Walls and cells so reduce eT 
as hardly to be recognized > Tenthredo, Cynips. 
as cups, 
Reduced to two small heaps, Many small butterflies. 
. Wall a broad plate, Forficula, Acridium, ete. 
Wall (fibrillar substance) 
absent. 
(a) Cells in 4 groups, Dycticus. 
(b) Cells in 2 groups, dis- 
tinguishable by com- 
parison with neigh- 
boring cells, 
(ce) Not so distinguish- \ is 
able, i 
2. Large with rim, 
on 
O T O 
Aeschna. 
dimen 
If such a superior neural function is indicated by the testi- 
mony and work of the earlier writers, it may well be asked 
whether recent neurological methods will bring out the struc- 
ture of the hexapod brain as well as they have that of the other 
invertebrates and that of the vertebrates, and whether they 
will lend this view support. First, it may be noted that the 
physiological experiments of Binet (’94), which are those of 
C. Cups unrecognizable even as ru- ) Hanipiors. 
