30 janvier 1970
Dear Marshall,
I understand from the paper of Gordon Sato in PNAS that you have developed a series of elegant micro-assays for the enzymes of catecholamine, acetylcholine, serotonin and GABA biosynthesis and catabolism.
I have left the nematodes which do not allow me to do what I would like.  I am turning now to work on mouse nervous system and mouse cell cultures.  I have of course no experience in the field, but I would very much like to have in hand the techniques for the study of the transmitters.  If you have no objection, I would be very grateful for a detailed protocol for these enzyme and transmitter assays.
What is new with nematodes with mouse neuro-blastoma and other cells in your lab?  Is there any chance to see you around Paris in the near future?
With very best wishes,
Yours sincerely,
Francois Jacob