300 The Brain of the Locust. [April, 
are surrounded by a lose net-work of anastomosing nerve fibers 
continuous with those of the antennal nerve, and with scattered 
nucleated cells, which become very numerous in the antennal 
nerve. The nerve fibers are stained reddish by the picrocarmine, 
Turning now to other orthopterous insects, Flogel mentions 
Acrydium, but states that he had no serviceable preparations, and 
after describing the brain of Forficula, the ear-wig, says: “ As I 
observe in Acrydium, the cells and fibers in this animal are espe- 
cially large, and these objects invite further investigation.” 
Flogel’s photograph and description of the brain of Forficula, a 
representative of an aberrant family of Orthoptera, and Dietl’s 
beautiful figures and descriptions of the brain of the molecricket 
(Gryllotalpa vulgaris) and the cricket (Acheta campestris), show 
that the orthopterous brain, judging from these representative 
forms, is constructed on a common type, the most variable part 
being the calices of the mushroom body. 
From these facts we should judge that, on the whole, the locusts 
were as highly endowed intellectually as any other insects, with 
the exception of the ants, bees, or wasps, 2. ¢. , the social species ; 
for in these forms the insect brain reaches its highest development, 
as we might expect from the wonderful instincts and power of 
reasoning exhibited by these social species; while in a number 
of insects the brain is less developed than in the locust. It would 
thus appear that, as in the vertebrates, there are different grades 
of brain-development, considerable extremes existing in the same 
sub-class of insects, as for example, in the same sub-class of 
mammals. 
The brain of the bee and ant, as shown by Dujardin and 
demonstrated by Dietl and Flégel, is constructed on a higher, 
more complicated type than in the other winged insects, owing to 
the much greater complexity of the folds of the calices or folded 
disk-like bodies capping the double stalk of this organ. 
[ To be concluded. | 
