18th March, 1966. Dear Professor Spiegelman, I wonder if you could send me slopes of your two strains A19 and Q13. I am having a little bit of difficulty with the in vitro phage protein synthesis due to the presence of RNAase. Our in vitro experiments have shown that three protein types can be distinguished. Early proteins (RNA replicase), mid proteins (unidentified) and late proteins (coat). Their syntheses are quite distinct and have different time courses. In vitro preliminary experiments show that the phage RNA induces the replicase but the synthesis has an extended lag - similar to 'Nisman' in vitro [beta]-galactosidase lag or the lag he and I observed for alkaline phosphate. I am wondering how similar Q[beta] is to our Z1K/1. Could you tell me its base-ratio and coat-protein composition? We have done both and found them quite distinct from MS2, R17 etc. Finally I was wondering how things are progressing with regard to the possibility of my coming to work in your lab for the next year or so. Do you know anything definite yet? Probably after a stay in America I may well come back here and work with Martin Pollock and Bill Hayes who are organizing a new Department on this site - the building of their department is in progress but won't be complete for 18 months or so. Looking forward to hearing from you. Yours, D.H.L. Bishop.