XVI CONTENTS. 



CHAPTER XX. 

 THEORY OF THE DISEASE. 



Resume of the various supposed causes of disease (439, 440). 

 Vastator (441). The disease (443). Condition of plant causing 

 death (444, 445). Effect of disease on wild plants (440). On 

 cultivated plants (447). Propagation from diseased sets (448, 

 449). As to cessation of disease (450). Relation of health of 

 plant to the insect (451, 452). PAGE 111. 



CHAPTER XXI. 

 FUTURE PROSPECTS OF THE DISEASE. 



Mischief done to esculent vegetables, &c., by vastator (454). Dura- 

 tion of insect pests : historical analogies (455). Probabilities as 

 to increase of the plague (456, 457). Aphis brassicae (458). 

 Insect destroyers of vastator (459). Probable result of disappear- 

 ance of vastator (460) ; of continuance (461) ; of increase (462). 

 Concluding remarks (463). PAGE 115. 



CHAPTER XXII. 

 ARTIFICIAL REMEDIES FOR THE POTATOE DISEASE. 



Division of subject (464). Destruction of Aphis considered : by 

 human means (465) ; by tobacco (466). Effects of water, thunder- 

 storm, on Aphis rosae (467) ; on vastator (468). Burning infected 

 leaves (460)- Effect of leaf-burning in beet (470). Quicklime 

 (471). Ducks and soft-billed birds (472). Coccinellse and ich- 

 neumons (473). Wheat (474). Early ripening (475). Early 

 potatoes (476). Autumn planting (477). Recapitulation (478). 

 Contagion (479). Burning infected haulms (480). Isolation of 

 crops (481). Means to be adopted over large districts (482). 

 Same means for all crops (483). Prppagation from healthy sets 

 (484). Generation of fibre (485). Means of inducing this (486). 



