Chimæras Dire: Transplantation of Heads of Insects

Abstract

WITH some astonishment I notice my friend, Dr. W. T. Caiman, agreeing with the German authors Hans Blunck and Walter Speyer in his letter to NATURE of July 5, p. 11, entitled “Chimæras Dire,” which is written with much sarcastic humour, but little knowledge of the subject. The title itself is misleading. Walter Finkler has never claimed to have produced Chimæras in adult insects, a term signifying in biology “simultaneous development of parts compounded from tissues of different species (or races); he has merely studied the possibility of replantation of heads and described the results thereof. He has neither written that “The head of a herbivorous water-beetle persuaded a carnivorous body to be content with, and seemingly to digest, a vegetable diet,” nor that “a Dytiscus strove to moderate the colourings of its wing-cases to suit the sober tastes of its new Hydrophilus brain.” The only part of Finkler's work referring to nurture (Archiv f. mikrosk. Anatomie u. Entwickl.mechanik, xcix., 1923, p. 113) alludes to the passage of coloured algae through the re-established connexion between the cut ends of the “sophagus in homoplastic experiments on the replantation of Hydrophilus-heads, while the assumption of a darker hue after heteroplastic replantation of a Hydrophilus-head to a Dytiscus-body refers to the yellow crossbars of the thorax in the swimming beetle (pp. 127–128), a result Finkler ascribes to the influence of eyesight, but that can perhaps be more readily explained on the assumption of tyrosinase diffusing from the head to the thorax.