Published online by Cambridge University Press: 14 April 2009
Congenital defects due to genes are the static end results of abnormal processes in embryonic development. Are these ‘burnt out’ and no longer in operation later in life, or do they continue as active physiological processes? To answer this question, thirteen genes with comparatively trivial morphological effects have been subjected to a screen test. For eight of them (bp, f, Ts, Sd, un, se, Os and Ph) a prima facie case has been established for the existence of continuing processes of one kind or another. For the remaining five genes (dn, Pt, T, vt and Miwh) there is no such evidence though the possibility remains that such processes might be detectable by different means.