CONTENTS 



Chapter * Page 



Neurospora 12-18 



Hymenomycetes 12-19 



Paramecium 12-19 



The Adaptability of Yeasts for Uniting. . . . 



Biochemistry and Experimental Cytology 12-19 



The Necessity for Direct Tetrad Analyses . 12-20 



13 Segregation, Variation and Recombination. ... 13-1 



Segregation of Mating Type Alleles 13-1 



Segregation of Colonial Types 13-1 



Variation and Colonial Types 13-5 



Variations in Relation to Life 13-6 



Recombination 13-7 



Transformation of Saccharomyces into 



Torulopsis 13-8 



The Instability of the Mating Tjrpes on Sub- 

 culture 13-8 



14 Variation in Growth and Fermentative Capacity. 14-1 



The "D" Family 14-1 



Variation in Growth and Gas Production. . . 14=5 



Gas Evolved Versus Growth 14-6 



Range of Variability 14-13 



15 Depletion Mutations 15-1 



Relation of Pink Color to Adenine and 



Methionine Synthesis 15-1 



False Mutations 15-4 



Depletion Mutations 15-4 



16 Adaptation in a Yeast Unable to Utilize Glucose 16-1 



Adaptation to Glucose Utilization 16-2 



Adaptation to Glucose on Lactate Medium . . 16-10 

 Adaptation on Standard Peptone Glucose 



Broth 16-10 



Crosses and Backcrosses with Strain No. 97 16-10 



The Mechanism of Adaptation 16-10 



17 Back-Mutation and Progressive Mutation .... 17-1 



Adaptive Fermentation of Galactose without 



Formation of New Cells 17-1 



Adaptation by "Back-Mutation" followed by 



Selection 17-1 



Progressive Mutation 17-4 



The Origin of Lactose Fermenters 17-5 



Unequal Crossing Over and Evolution .... 17-5 

 A Hybrid between S. Cerevisiae and S. 



Fragilis 17-8 



xiv 



