The relation of size and age to rate of tail regeneration in lebistes retieulatus

Abstract

1. Tail-webs of female guppies were cut off transversely, and the rate of regeneration determined at ages from birth to three years a) in fish growing under normal aquarium conditions; b) in fish whose growth was stopped by food restriction; c) in retarded fish during resumed growth. 2. The percentage of a defect restored after 20 days in normally-growing fish falls with age and size. The curve of its decline is a mirror-image of the growth curve in body length. 3. In checked fish which are not growing, the regeneration rate is about the same as in full-sized littermates: in checked fish which have resumed growth it is much faster. 4. Regeneration rate in females is determined chiefly by the status of general body-growth. As body-size approaches its asymptote for a given set of conditions, regeneration rate falls to a basal level. When growth is resumed it rises again. 5. Old checked fish which fail to grow when transferred to better conditions may still respond by a rise in regeneration-rate. 6. The basal level of regeneration is higher in males than females, and in wild-type compared with fancy-tailed males. 7. The histology of the regenerative process in Lebistes tail-web is described and illustrated. © 1958 S. Karger AG, Basel.