All rights reserved. Click here to order online. Most mutants which arise in any organism are more or less disadvantageous to their possessors. Mutants are known which diminish the quantity or destroy the pigment in the eyes, and in the body reduce the wings, eyes, bristles, legs.
Many mutants are, in fact, lethal to their possessors.
Mutants which equal the normal fly in vigor are a minority, and mutants that would make a major improvement of the normal organization in the normal environments are unknown. Nilsson, p. 1186. In the best-known organisms, like Drosophila, innumerable mutants are known. Goldschmidt, p. 94. Fruit flies refuse to become anything but fruit flies under any circumstances yet devised.