The Lister Institute of Preventive Medicine, ~ Chelsea Bdge. Rd., =. London, S.i/.1., England, ef Professor Je Lederberg, . Department of Genetics, University of Wisconsin, ‘Madison, Wisconsin, U.S.A, i 4 Dear Josh, . _How are things at Madison? Hot enough I have no doubt, but perhaps you are away. When-are you going’ to send-us a tape letter? ~~ ee .. What do you think of the idea of writing the abortive transduction of motility paper now? _ Admittedly there are a great many more things which:we could do, but the prospect extends indefinitely, and I think what we know at present will make a reasonably well-rounded-éff piece, for the micro= manipulation experiments I think now tie-in satisfactorily with thé trails, and’ so confirm the origi- . ‘nal hypothesis, and I think the quantal dé&stribution:of the. "gene-prodtict" is well enough established, The main gaps are (i) whether there is abortive transduction 'of*other characters, (ii) whether quantally . distributed, gene~product is in fact flagellum (or fagellum producing granule) (iii) whether decision trail or swarm is inherent in phage-particle before |absorbtion, ~ As to (i), thesé are some’ ways that might be worth trying, but this might be a long job, andfonly limited theoretical importanceg,.so I _ ‘think it might be left open.. As to (ii), I am not making much‘ progress, since I can't stain flagella reproducibly; and the good electron microscope at Mill Hill has just been burnt out. Anyway, I shall continue to work on this, and may have some results later. One point in one of your letters I did not ‘quite understand, that is the immediate segregation of motility when a cell with 1 “gene-product" divides; I have only managed to observe the actual moment of cell division once in such a case (and the result was the expected). Do you mean that you have actually seen séveral such cell divisions, or are you inferring from cases where motile cell is found to have produced one motile and ore static cell when re-examined a. few,minutes later? As to (iii), there are a lot of experiments waiting to be done, e.g. effect, of ‘multiplicity, lysogenicity, temperature and so on, but I don't see they need be, done at the moment. Furthermore, I don't think we need go into the evidence for simultaneous expressiqn of Hi and H,” in the case of SW543, though I think this is thd best clue we have on what is going on. '- Ineiden- ~ tally, we have since found’ that the apparently similar effect in the case of S$L28 is -begus, “it'was due to cross-reacting anti-body in the serum used; however, I have one other strain, I: think SW966, in which’ casual observation suggests that antibody for donor's antigen redu:es number of trails but does not abolishky, The question arises of how much theory, or speculation if you like, as to mechanism, should be included, I fell inclined to mention the two main possibilities (4) that the &ira piece is deficient in > “/some } re “some way_so it can't be. incorporated, and (ii) that it is. incorporated in:an abnormal way, perhaps as,side-erm Your unsuccessfull search for cells which have new Jatin latent H, antigen in progeny of abortively mtilised §: — 39543 thdh become very relevant. Do you think they | ths should be mentioned, or reserved for later? | If you agree it should be done now, I will start = on anskeleton draft, and send it you for gomment. I} am getting a bit bored with pedigrees and so on, We } seem able to get Ecells fairly regularly now; in an} expetiment last week of 57 motile cells picked, 6 died 10 gave non-motile} only, 31 gave between 1 and 10°}. motiles and 10 gave from 20 to 60 motiles, after over=}. night incubation, i;e, about 1/5 E results, ‘Droplets! of a collection of mtiles collected at same time and: plated on gelatin-agar gave.3 trails (c.35, 60 and. Mic 3 % Fe colonies) from abdut.1} surviving cells, some of which: - gave ‘about 1 swarm per 5 trails. , prgduced gmall groups of colonies, The only diss. §). crepancy is that no. swarms were obtained; from: manipy-s | . latorpicked motiles, though thé. phage celia wixture. re ha age a Not. mich other news. I and Cli thinking of lgoking into mechariisms - can now get ( dgregated) flagella o, c 8 to show up beatifully in darkground, but have not yet-{ . had any luck with Salsonella, though it can be done’) according to literature. . The trouble is it ds.s9.00 fb. .. pretty, it is hard to tear oneself away to So Se | - else. We.are just making up methykellulose solutions} — of viscosity about 1,000 ‘centipoise, te keep Reynold's)! nunber right for models. .° Low aay Se Oo é fa Bap, soar.