I know that you would want me to make the comment if it occurred to me, or I would not bother.
A propos your paper in PNAS, August 1957, p. 745: so far as I know, no one had induced mutation in "testtube [sic] genes",
near [?] observed its occurrence outside the intact cell. The nearest thing to it is the inactivation [mark to note, e.g.
Herriott; Zamenhof] of genetic activity by the usual reagents. Please instruct me if I have overlooked what you had in mind.
I doubt that anyone has yet made a powerful study of the point. We have too long had "good intentions" in the Gal