1. The correspondence between Lucien Ledoux and Mary-Dell Chilton was clearly not meant to remain private, as their letters were carbon-copied to several other investigators. I believe that further dissemination of these letters to others direcdy involved in the field was an excellent initiative.
2. The results published by the Tübingen group came from two doctoral dissertations, one by Waltraud Gradmann-Rebel and the odier by Birgit Leber, both under the direction of Vera Hemleben. Their dissertations, of course, contained much more information than what was published. This additional result is reported in their work: Glycosylated T4 DNA produces the appearance of a high-density peak, whereas DNAs from Streptomyces griseus, E. coli, B. subtilis, and Pneumococcus do not. These bacterial DNAs, when fed to Matthiola, are degraded and reutilized for endogenous DNA synthesis and produce no intermediate-density DNA peak.
1. This fact was later acknowledged by Hess himself. He observed that on one given plant, die phenotype could change from white flowers to heavy andiocyanin accumulation in the corolla and then reverse, depending on temperature and light intensity. These changes were also seasonal. In addition, he noted th viral infections (which were not considered earlier) also influenced anthocyanin production in his plants (Hess 1980).
2. One may wonder why it was so important to use plant mutants unable to perform a certain function (such as pigment or thiamin synthesis). Why not go direcdy for an added function, such as disease or herbicide resistance? The answer is twofold: First, disease or herbicide resistance genes were either not known or not well characterized at the time; second, these experiments were aimed at determining the feasibility of actually having exogenous DNA expressed in recipient plant cells. For this, a reasonable approach was to correct a known mutation with exogenous DNA known to contain thgene(s) performing diat very function.