PREFACE 



Carlsberg Brewery supported Hansen, the inventor of the pure- 

 culture technique; Sorenson, the inventor of pH; Kjeldahl, whose ni- 

 trogen determination is a byword; and Winge, who brought yeast 

 genetics into being. Joule determined the mechanical equivalence 

 of heat in a brewery laboratory. Modem statistics are based large- 

 ly on the work of Student, an employee of the Guiness Breweries in 

 Dublin. Beijerinck, whom many consider the most penetrating stu- 

 dent of the biology of yeasts of the last century, was largely sup- 

 ported by a brewery in Delft; and his successor, Kluyver, from 

 whose laboratory have come some of the very important advances 

 in enzymology and zymology has lived up to the standards set by 

 his illustrious predecessor. Henneberg's work was also supported 

 primarily by German breweries and we are indebted to him for the 

 discovery of food yeast, a source that may one day provide much of 

 the world's proteins and vitamins. Finally, Pasteur's germ theory 

 of disease has its origin in his demonstration that fermentation is 

 caused by microorganisms. He developed this concept of disease 

 in the course of his successful attempt to discover the cause of 

 spoilage of beer in the French breweries. It is safe to say that very 

 few industries have contributed as much to modern biological thought 

 as the brewing industry. 



In the tetrad analysis of heterozygous yeasts, we have encounter- 

 ed many cases of apparent non-Mendelian heredity. There have been 

 three phases in the interpretation of these phenomena. At first, 

 the interpretation was on a classical Mendelian theory assuming that 

 different alleles produced the same phenotype. When this view was 

 shown to be inadequate, the data wer*^ interpreted by assuming that 

 the cytoplasm contained autonomous entities produced by gene action. 

 This interpretation was also rejected, and at present genes are 

 assumed to respond adaptively to the environment, rather than as- 

 suming that autonomous C3rtoplasmic entities are produced. These 

 changes have resulted in the reinterpretation of many of the pre- 

 viously published experimental data. In this volume all data are 

 interpreted according to the current view and the history of changes 

 In point of view is not discussed unless it seems essential. 



Our data on non-Mendelian inheritance indicate that the current 

 views concerning the stability of the gene and the regular segrega- 

 tion of alleles are in need of revision. Some readers may interpret 

 this as support of Lysenko's theories of heredity. This is by no 

 means the case. Lysenko's views are based on (1) belief in Lamarck's 

 theory of the inheritance of acquired characters and (2) the view 

 that genes and chromosomes have no control over heredity. I have 

 shown that the gene may be readily affected by the environment, 

 but my data indicate that heredity and phenotjrpe are both under genie 

 control and that non-genic influences are practically non-esixtent. 

 Current editorial criticism of Lysenko consists largely of attacks 

 on the tenability of his scientific views. I believe this attitude is 



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