Sex [electronic resource] . inct, except that shecherishes the parasite instead of eggs—whichare absent. Giards work has been extended by thatof Geoffrey Smith, in a series of researchesremarkable for their thoroughness. In thecase of male crabs of the genus Inachus, forinstance, he found that castration, brought Fig. 15.—Forms of Abdomen in a crab, Pachygrapsus. A, o^a female; B, of a male; C, of a parasitised male approxi-mating to the female type. (After Geoffrey Smith.) about by Sacculina and the like, induced avery striking expression of latent feminineand female features. The crab develo
Sex [electronic resource] . inct, except that shecherishes the parasite instead of eggs—whichare absent. Giards work has been extended by thatof Geoffrey Smith, in a series of researchesremarkable for their thoroughness. In thecase of male crabs of the genus Inachus, forinstance, he found that castration, brought Fig. 15.—Forms of Abdomen in a crab, Pachygrapsus. A, o^a female; B, of a male; C, of a parasitised male approxi-mating to the female type. (After Geoffrey Smith.) about by Sacculina and the like, induced avery striking expression of latent feminineand female features. The crab developedegg-carrying abdominal limbs like those of afemale and it produced eggs. The normalcrab is not in any sense a hermaphrodite,but the effect of castration is the developmentof the latent characters of the other sex. Potts has studied the castration of malehermit-crabs by Peltogaster and of maleshore-crabs by Sacculina. In the former,the male characters persisted; in the latter,though the castration was incomplete, some. THEORY OF SEX-DIMORPHISM 85 female characters appeared. Smith and Pottsare both of opinion that what happens is achange of the metabolism of the crab on tofemale lines. In Inachus, the putting on ofexternal feminine characters preceded theappearance of the ovaries, so that the theoryof a specific secretion passing from the gonadsto the body is in this case excluded. Smiths theory has an important bearingon the significance of sex and on the roleascribed to internal secretions. Without goinginto technicalities, let us seek to understandmore precisely what he means by saying thatthe parasite disturbs the general metabolismand that this affects the expressions of a normal female crab the ripening ovarytakes up lutein and fat; this seems to stimulatethe liver to make more, and to lessen anotherof its functions, namely, making glycogen(or animal starch) which is used in the ripening female the blood becomesprogressively charged with fat and lute
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