Antigen-induced secretion in the optic gland of Octopus vulgaris.

The optic gland of the octupus responds to a variety of foreign proteins--1 to 2 days after the injection--by the mass production and release of a particulated material. In the electron microscope the antigen-induced substance shows as a non-membrane bound particle of size about 30 nm. When released into the blood it does not disintegrate instantly. The chemistry of this material, which is probably identical with the optic gland hormone, is not known. However, non-vesicular storage and release as well as the abundance of tubular mitochondria suggest that the hormone is a steroid. The optic gland hormone, which is known to control sexual maturation, feeding and death in Octopus, appears to be involved in a defence mechanism against non-octopus proteins.