iv PREFACE 



on the origin and evolution of sex, based primarily on conditions in 

 the Protozoa, but including questions about all of the microorganisms. 

 It is hoped that this volume will reveal to readers not only that 

 "sex" is widely distributed among microorganisms, but that many 

 groups appear to get along without sexual reproduction, at least 

 for indefinite periods of time, and that the details of sexual behavior 

 vary widely among and within the different groups of microscopic 

 organisms. 



D. H. Wenrich 



