VIII.—On the Suppression of Tangled in Drosophila pseudo-obscura

Abstract

The results of the interaction of any two genes cannot yet be foretold with any degree of accuracy. This is another way of saying that our knowledge concerning the problem of the gene and development is still very meagre even in its grosser details. The work of Schultz (1935) and others has shed much light on the reasons for such phenomena as the disproportionate modification of vermilion by purple (Bridges and Morgan, 1919), and for many other observed effects following the combination of eye-colour mutants, but explanations for similar phenomena in other parts of the body, for instance, the non-additive action of bristle modifiers found by Plunkett (1926), and the interaction of the wing and bristle mutants of Lebedeff (1935), are of a somewhat more speculative nature. The accumulating data on these problems do not yet allow the empirical method to be dispensed with in seeking the answer to the question: What will happen when these two mutants are put together? From another point of view, the interaction of two genes, when it can be observed, is a useful method of approach in the investigation of genetic control in development, and has been used by various workers such as Csik (1934), Goldschmidt (1935), Dunn and Coyne (1935).