TABLE OF CONTENTS. 



Page 

 PREFACE to the German edition 3 



IXTRODUCTIOX. 



Section i. THE NATURE OF DISEASE. 



1. Limitation of the conception of disease 5 



2. Production of the disease 8 



3. Relation of the plant to its environment lO 



4. Parasitic diseases 13 



5. Epidemics 19 



6. Artificial immunization and internal therapy 23 



7. Predisposition 25 



8. Predisposition and immunity 27 



9. Inheritance of disease and of predisposition 31 



ID. Degeneration 34 



Section 2. HISTORICAL SURVEY. 

 Historical Survey 41-70 



APPENDIX 70 



DETAILED EXPOSITION. 



Section i. DISEASES DUE TO UNFAVORABLE SOIL CONDITIONS. 

 Chapter I. The location of the soil 72 



1. Elevation above sea level 72 



a. General changes in habitat. 



In relation to herbaceous plants 72 



Development of the aerial axis of woody plants 76 



Adjustment of the root body of woody plants 78 



b. Special cases of disease 81 



Retrogression in the cultivation of the larch 81 



Lack of success with tropical plantations 84 



2. Slope of the surface of the soil 86 



a. Too steep slopes 89 



b. Growth of stilts, elevation of the roots of trees 92 



c. Too deep planting 98 



Too deep planting of trees 98 



Too deep sowing of seed : 106 



Roots from the tips of grain seeds ' 116 



3. Greater horizontal differences 120 



Glassy grain kernels 129 



4. Continental and marine climates 131 



5. Influence of forests 134 



Chapter II. Unfavorable physical constitution of the soil 138 



1. Limited soil mass 138 



Root curvature 138 



Dwarf growth (Nanism) 142 



Too thick seeding 147 



2. Unsuitable soil structure 148 



a. Light soils 148 



Disadvantage of sandy soils 148 



Lowering of the ground water level i5o 



The dying of alders i5.^ 



Street planting I53 



Effect of drought on field products I55 



Effect of drought on germination 157 



Treatment of tree seeds IS8 



Blasting in grains and legumes 160 



