CONTENTS 



I. Introduction 5',45 



II. Methods 24G 



1. Elimination of the oil 246 



2. Soaking in water 247 



3. Moisture content of the soil 247 



4. Culture media 247 



0. Preparation of the soil 248 



6. Planting 249 



7. Temperature 250 



Iir. Experimentation and discussion 250 



1. Effects of the period of immersion and the moisture content of the soil. . .250 



2. Long periods of immersion 255 



3. Types of abnormalities 256 



4. Dry membranes 258 



5. Mutilated membranes 260 



6. Moisture content of the grains 264 



7. Variation in soil moisture 266 



8. Other oils 269 



9. Summary of conclusions 271 



Bibliography 272 



