PREFACE 



Study of the yeast cell began with the announcement of the cell 

 theory by Schleiden and Schwann. The difficulties encountered in 

 interpreting the numerous observations were only partly due to 

 technical obstacles. Modern concepts of cellular organization have 

 been as helpful in interpreting the yeast cell's structure as the 

 modern knowledge of nutrition has been helpful in understanding 

 its metabolism. We have finally been able to show that the yeast 

 cell is a conventional cell with chromosomes, nucleolus, hetero- 

 chromatin, centrosomes, and mitochondria. 



Because yeast is an article of trade and has been available to 

 biochemists in considerable quantities as a source of living proto- 

 plasm, modern biochemistry is based largely on the study of en- 

 zymes isolated from yeasts. Winge and Laustsen showed that yeasts 

 were also acceptable genetical material and our own work has con- 

 siderably extended the knowledge of yeast genetics; we have con- 

 structed the first chromosome maps of yeasts and have developed 

 new concepts of the nature of the hereditary apparatus which have 

 been confirmed by tetrad analysis of hybrids with well marked 

 chromosomes. 



This volume reviews the genetical and cytological work thus far 

 achieved in our laboratory during the last eight years by Mrs. 

 Lindegren and me and our assistants, first at Washington Univer- 

 sity, St. Louis, Missouri, and more recently at Southern Illinois 

 University, Carbondale, Illinois, and includes discussions of work 

 carried on at the same time by others associated with us, notably 

 Dr. Folke Skoog, Dr. S. Hestrin, Dr. S. Velick, Dr. Michael 

 Doudoroff, Dr. Sol Spiegelman, Dr. J. M. Wiame, Dr. J. O. Lampen, 

 Dr. E. L. Tatum, Dr. Caroline Raut, Dr. J. S. Rafalko, and Mrs. 

 Margaret Rafalko. It was first organized in a series of lectures 

 given at the University of Washington, Seattle, in the spring of 1947 

 while I held the Walker Ames Professorship of Botany there. 



Our work has been made possible by the continued and generous 

 support of our laboratory by Anheuser-Busch, Inc., for which we 

 are deeply grateful. Subsidiary grants have been received from 

 the U. S. Public Health Service, the American Cancer Society, 

 Washington University, Southern Illinois University, and the Ameri- 

 can Philosophical Society. The support from Anheuser-Busch, 

 Inc. is in line with the honorable tradition of breweries which have 

 generously supported so many investigations in pure science. The 



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