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In the Ostracoda, Zenker describes a gland situated in the base of the inferior antennae, and opening at the extremity of an extraordinarily long "spine." The adherent feet are retracted within the rather opaque anterior part of the shell. Pupa of Sacculina purpurea, magnified 180 diam.
It penetrates into the crab in its larval stage, and passes entirely into the crab's body, where it develops a system of branching root-like processes. When mature the body of the Sacculina containing its generative organs forms a projection at the base of the abdomen of the crab on its ventral surface, and after this is formed the crab does not moult.
In these also the brood bursts out in the Nauplius-form, and speedily strips off its earliest larva-skin which is distinguished by no peculiarities worth noticing. A pair of similar filaments spring, in the larvae of the Cirripedia and Rhizocephala, directly from the brain. Nauplius of Sacculina purpurea, shortly before the second moult, magnified 180 diam.
Young of Peltogaster socialis on the abdomen of a small Hermit Crab; in one of them the fasciculately ramified roots in the liver of the Crab are shown. Animal and roots deep yellow. Young Sacculina purpurea with its roots; the animal purple-red, the roots dark grass-green.
When Sacculina is present these substances are absorbed by the parasite; the ovary is deprived of them, and therefore atrophies. In the male the parasite requires similar substances, and its demand on the blood of the host stimulates the secretion of such substances, so that the whole metabolism is altered and assimilated to that of the female.
So, drawing nutriment from the Doctor's historic brains, and from Leo's, I fall back into worse than a dodder, a torpid violator of the Law of Work, a hopeless Sacculina!
It must however be noted that the Sacculina itself is hermaphrodite, with ovaries much larger than the testes.
Fancy the consolation a person of my indolent Sacculina temperament might have derived from the untimely fate of Cassandra, oppressed with knowledge in advance of her day and generation! There was the gymnasium for the beaux; and for the belles bona fide gardens, with walks and arbors covered with ivy and flowering vines whose roots rested in great stone vessels filled with earth.
Smith's theory therefore is that the action of the testes in metabolism is rather to take something from the blood than to add something to it, and that it is this subtractive effect which influences the development of somatic sexual organs. Sacculina is one of the Cirripedia, and therefore allied to the Barnacles.
Compulsory insurance was tried in the practical and economical Swiss city of Basle and given up, because it was found that each year it was the same small class who reaped the benefit of the insurance. The crab gained nothing and the Sacculina became rapidly impotent.
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