Istanbul, January 9, 1943
Dear Dr. Heidelberger,
On July 20, 1942 I wrote you, asking you the favor of sending the reprints of your papers Journal of Experimental Medicine Vol. 75 p. 35 and 135, whose abstracts I had read in the last "Chemical Abstracts".  Our bibliographic situation here is worse now than before.  As I wrote you, we do not get any journals from the United States for formal reasons.  I had ordered on my own costs to Chemical Abstracts.  Unfortunately, these cannot be forwarded from the United States to neutral countries.  Therefore I am not informed at all about the development in our science overseas.
The main purpose of my letter is the following.  I've repeated now my earlier work about the gravimetric determination of complement, modifying the message according to your technique.  I investigated the precipitation of arsanil-antigens by immune sera and used a large excess of the guinea pig serum, recommended by you.  I am glad that I found in agreement with your work a regular increase of weight if active guinea pigs serum was added.  Moreover I determined quantitatively the amount of antigen in the precipitate and arrived as an interesting conclusions about the action of complement.  Since the American government want to encourage the publication of Turkish scientific papers in the United States, we sent the manuscript by the U.S. Information Office here to the Journal of Immunology, asking the editors to read the proofs in America. I hope you will be so good as to do me the service again.
I have read very attentatively your three papers on complement determination.  Please allow me the following remarks.  On page 682 of the Journ. of Experimental Medicine you mentioned a 5% suspension of red blood corpuscles and state that it contains 830.000-1,500.000 cells per cmm. How is that that possible?  That would mean that the sheep blood contains more than 10 millions of red cells per cmm. On page 697 of the same Journal you use Ponders formula for the calculation of the red cells surface.  This formula has been misprinted in Ponders original paper.  Actually he used a right formula, which furnishes a much larger value, approximately 18 times larger.  Of course your calculations about the surface should be corrected by this factor.  In my own paper I do not touch these points, therefore I am communicating them to you by this letter.  I hope to have quoted your own results in a right manner in my paper.  Should I have not taken account of some new results, please ascribe it to the impossibility to get the American Journals since July 1942 and the J. of Exp. Med. since Volume 74.
With the best wishes for 1943 and many thanks for your trouble
Yours very sincerely