236 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
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 Forhcula, the ear- wig, says : " As I observe in Acrydium, the 
cells and fibers in this animal are especially large, and these objects in- 
vite further investigation." Flogel's photograph and description of the 
brain of Forhcula, a representative of an aberrant family of Orthoptcra, 
and Dietl's beautiful figures and descriptions of the brain of the mole- 
cricket (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 excep- 
tion of the ants, bees, or wasps, i. e., the social species; while in a num- 
ber 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 in the same sub-class of mammals. 
The brain of the bee and ant, as shown by Dujardin and demonstrated 
by Dietl and Flogel, 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. 
STRUCTURE OF THE BRAIN IN THE EMBRYO LOCUST. 
Much light may be thrown upon the structure of different parts of the 
adult brain if we can trace their origin in the embryo, or in the larval 
and pupal conditions. Hence, we have, with what material we could 
obtain, made a series of sections of the embryo and different stages of 
the larva and pupa, with some results of considerable interest and im- 
portance. No one has yet examined the brain of the embryo insect. The 
only observer who has studied the brain of the larva, as compared with 
the adult, has been Flogel. Speaking of the cockroach, he says : 
Of especial interest would be an investigation of the development of the separate 
parts of the brain. The difficulty of making preparations of small heads has been such 
that no particular results have been reached. Still, I can say this much, that in small 
creatures 7-8 mm in length all the parts are present, only of a finer and more delicate 
structure than in the large adult 25 mm in length. 
He says that in the Hymenoptera he has discovered much concern- 
ing the development of the parts of the brain ; that in bee larvae the 
calices are present, though very small and with thin walls. The peduncle 
and trabecula have reached their ultimate proportions more nearly 
than the cauliculus, which is still very thin. In the larval ants the cen- 
tral body and entire mushroom bodies are present, though an early larval 
