April 24, 1945
Dear Enrique,
I have read your letter, Seifter's dissertation, and the review article (which I had not seen, being still way back on the Nov. and Dec. journals) with the greatest interest.  Since you have independently adopted much the same principles as we have, I agree that nothing would be gained by going into details.  All of this happened just as the page proof came in, so (at great expense) I have made most of the changes you suggested, and I believe you will be satisfied when you see the paper in the May J. Exp. Med.  From the brief conversations we had, I did not realize that the gap between our methods had narrowed so much.  Under the circumstances, I do not think the original version was ungenerous, for when a really misleading method is recommended in half-a-dozen papers over a couple of years it is surely up to someone to call attention to its shortcomings.  However, now that I know you are on the way to correct the situation yourselves I really feel much happier that it is going to be going to be done that way.
Speaking of generosity, what about Seifter's disparaging--and silly--appraisal of the quantitative method in his dissertation?  I'm also waiting for your group to write a new paper on that and correct much of the contents of your original one.
Now for Seifter's work.  The method of initial concentrations had done a lot to straighten matters out for you, but it does not go far enough.  If he now gets almost the same results as we do with his C it is only because one would necessarily be luckier with the new method than the old one.  As we see it here, he is still working in the dark with a very arbitrary and cumbersome method, and with no positive assurance that his reagents contain all required components in excess, subscribing to this requirement in principle only.  What is the objective to running an old-fashioned titration at any level of hemolysis you want?  Also, why do you report percentage reactivations?  Surely no one yet knows the relation between this result and quantity of component.  If Maltaner is right it is anything but a proportional one.  And why do you talk about "concentrations" and "effective concentrations" when other publications of yours show that you realize that the terms can only cause confusions when you really mean "titers"?  Also, Seifter's use of the word "unit" is so loose as to deprive it of all meaning.
It seems to me that in spite of our agreement on principles our methods of putting them into use are so divergent that too great a gulf still exists between our laboratories.  I should like very much to have a San Francisco Conference of our own, where we can sit down and thrash out these matters and get to the bottom of it all.  So I cordially invite you and Seifter, and Pillemer if wants to come, to drop in at my laboratory, preferably some time before Seifter's work gets to the proof stage, and you all, and Mayer and I, the only two of our complement team left, will fight it out until some agreement is reached.  Otherwise, I fear the same situation with arise again, and I don't like to indulge in polemics with my friends any more that you do.
I expect to be until away until the end of May, so come along any time after that.  Bring your fiddle and we'll play some Haydn sonatas (unaccompanied, Op. 93, I think) and the Brahms horn trio we have any energy left.  How about it?
Looking forward to a lively time,
As ever,
Michael Heidelberger