Asymmetry of the Nervous System in the Larva of Harpyia

NOTHING has been published in regard to asymmetry of the nervous system of arthropoda, as far as I have been able to ascertain. In dissecting a number of the larvae of Harpyia (Bombyx) vinula, I found that the nervous system, instead of extending in a direct line in the ventral region of the larva, as is common in insect larvae, curved outward laterally between the first and second thoracic ganglia, as seen between c and d in figure 6. This curving, wlfich was toward the left in six larvae examined, is to avoid interi’erence with the duct from a sac, or gland, which, opens out between the first and second thoracic ganglia. This gland, represented in the figure by a dotted line, secretes a liquid, said to contain salicylic acid, which the larva ejects, as a means of defense, when disturbed. Tile duct of this gland opens by a transverse cleft, figured by Miller, on the ventral side of the first segment posterior to the head. Further details in regard to this gland are unnecessary as a good description of it has been given already by Rengger. In the earlier stages of the larvae of Harpyia, the nervous system turns considerably out of the direct line, in order to allow the duct of the gland to pass,