SEX CHANGELINGS.

Auckland Star, Volume LXV, Issue 153, 30 June 1934, Page 8 (Supplement)

SEX CHANGELINGS.

CURIOUS INSTANCES. IN FISH AND BIRDS. ~ NATURE RESTORES BALANCE. A number of small fresh-water fishes from Mexico, knovrn as sword-tails, now in the aquarium at the London Zoo, have undergone a remarkable metamorphosis—nothing less than a complete change of sex, says a writer in the London "Observer." Though a similar phenomenon is recorded in the vivid scarlet Sebastes, or scorpion fish, of sub-tropical waters, it may be more conveniently observed in the sword-tail, which by its small size and hardiness has for long been an established favourite, with aquarists. In the male of this viviparous fish one of the lower fins is curiously adapted to serve as a pairing organ, and a similar transformation may occasionally be effected in the females after they have produced several broods of young. The transformation is complete, involving the development of the swordlike extension of the caudal fin, normally! a strictly male characteristic. The reason for this change of sex has been explained theoretically by the fact that the females usually far out-number the males, and that Nature would seem to be taking drastic steps to equalise the sexual ratio. Whatever the explanation, sexual changes amongst animals are less infrequent than many suppose. Neither are such reversals restricted to fishes. An early record of a sexual change in a comparatively highly organised creature refers to a barndoor cock, which, in 1474, was actually accused of laying an egg. This irregularity occurred at Basle, in Switzerland, and the bird having been formally charged with witchcraft, was tried, sentenced and burnt, together with its egg. At that early period such an outrage of Nature naturally aroused the greatest suspicions, crystallised in the doggerel rhyme:— A -whistling maid and a crowing hen Are neither fit lor God nor men. Indeed, were it not that the fourteenth century also saw pigs solemnly tried, convicted and hanged for misdemeanors, and whole colonies of rats exorcised by' the Church, one might be tempted to dismiss tho occurrence as a flight of medieval extravagance. Recent Research. Recent researches have, however, fully justified our crediting the story of the laying cock at Basle. Professor Crewe recently investigated the case of a three-year-old Buff Orpington that suddenly broke a blameless record, both as a layer of eggs and a model mother, by taking on all tho characteristics of her own husband. She ceased to lay, developed spurs, crew lustily, and the following season assumed male plumage and became a father. The batracians, which stand midway between the reptiles and the fishes, present equally strange but slightly less spectacular sexual vagaries, and in these animals the elements which determine their sexual activities may be overridden by artificial means. Frog spawn kept at a high temperature or in acidulated water ensures a preponderance of male tadpoles; while if the ora is kept merely moistened the sexual pendulum swings in the opposite direction. Further, a substantial increase of males is ensured if the female enn be induced to retain tho eggs a few days longer than the normal period of deliverance. The Toad. Every male toad is a potential female, and some very curious reversals have Ik'cii brought about. If by a very slight operation the latent female in the male be caused fully to assert itself, the union of two ''fathers ,, results in a high preponderance of male offspring. Not only disease or surgery may alter a creature's destiny, for in the case 01 some crustacerfn parasites produce similar results. Attached to the undersurface of the common shore crab between the abdomen and the tail fin one may often find a limtiless and almost shapeless mass of indefinite colour and leathery consistency. This is a degenerate crustacean Saculina, which in its early days is a free swimming animal, but ends ita career by becoming attached to a crab. The crab so attacked is doomed, but before it succumbs, however, it may change sex, the males even assuming the comparatively feeble claws characteristic of the females. Our native oyster undergoes a periodic change of sex, and although the precise cause it still debatable, it may have some such foundation as that which animates the sword-tail fish. A native oyster may change from male to female as mauy as four times in thirteen months, a procedure which is, curiously enough, absent in the American and Portuguese species.