DEPARTMENT OF CXEMISTRY BERKELEY 4, CALIFORNIA UNIVERSITY OF CALIFORNIA October 2, 1959 Professor Joshua Lederberg Department'of Genetics Stanford Medical School Palo Alto, California Dear Josh: Here are SORYZ copies of the stuff that Harold Weaver collected which we thought you would like to distribute to the members of WESTEX. I am looking forward to seeing the m inutes of our last meeting, especially since we were not there at its final summation. Also, I am wondering if you have an opinion regarding the num- ber of organisms per gram of rock that one m ight find, say on a high mountain, or per gram of dry sand from a similar loca- tion. Also, do you have some idea of the bacterial population of various ldslds of soils? .GrTtings and very truly yours, / Melvin Calvin Professor of Chemistry MC:mt Encs.