Some Effects of Colchicine on Transverse Fission in the Planarian, Dugesia dorotocephala

Abstract

Child (1910) showed that transverse fission in Planaria dorotocephala (= Dugesia dorotocephala) could be stimulated by decapitation. He believed that the cephalic ganglia inhibited asexual division and that their removal permitted fission to occur. F. S. Miller (1937) demonstrated a fission-inhibiting effect by treatment of decapitated planaria with strychnine. Solutions of M/300,000 were used. Results showed that 54 per cent of decapitated worms (controls) divided, whereas only one per cent of strychnine-treated decapitated worms underwent fission. The work of Owen, Weiss and Prince (1938) indicates that glutathione and dibenzanthracene stimulate regeneration and fission' rates in planaria, but several derivatives of glutathione do not. Chu and Pai (1944) have mathematically shown a relationship between fission frequencies and regeneration gradients in an annelid, Stylaria fossularis. Hyman (1951) mentions that those planaria which reproduce asexually also possess high powers of regeneration, and gives two examples of planarian species in which the development of pharynx and eye spots precedes fission. A. and H. V. Bronsted (1953) stated that regeneration in starved planarians was accelerated by ribonucleic acid (RNA). In addition, they mentioned that RNA inhibited asexual division in planaria used in their experiments. Recently, Kanatani (1957 a, b) has shown low concentrations (1/10,000,000-1/10,000) of heparin to stimulate fission and higher concentrations (1/2,000-1/1,000) to inhibit it in decapitated planarians (Dugesia gonocephala). Crowding of intact worms inhibited fission in these planarians. The effects of colchicine on planarian regeneration or reconstitution have been studied previously by McWhinnie (1955), who submitted the