"X CONTENTS. 



CONVERSATION XXII. 



ON ARTIFICIAL SYSTEMS OF CLASSIFICATION OF PLANTS. 

 Analytic Method. Flore Francoise. System of Linnaeus. - 256 



CONVERSATION XXIII. 



ON THE NATURAL SYSTEMS OF CLASSIFICATION. 



Method of Tatonement. Method of general Comparison of Mr. Ad- 

 amson. Method of Subordination of M. De Jussieu and M. De 

 Candolle. Comparative Importance of Organs. Organs of Repro- 

 duction and of Nutrition. .... 265 



CONVERSATION XXIV. 



ON BOTANICAL GEOGRAPHY. 



Geographical Distribution of Plants. Difference of Habitation and Sta- 

 tion of Plants. Botanical Regions. Their Boundaries. Various 

 Modes of conveying Seed from one Region to another. Proportion 

 of Monocotyledons in the Vegetable Kingdom. Dycotyledons increase 

 towards the Equator, Acotyledons towards the Pole. Ligneous 

 Plants increase towards the Equator, Herbaceous Plants towards the 

 Pole. Annuals most common in Temperate Climates. Greater Va- 

 riety of Plants in hot, than in cold Climates. Social Plants. 27& 



CONVERSATION XXV. 



ON THE INFLUENCE OF CULTURE ON VEGETATION. 



Races. Varieties and Variations, derived from Species.-^-Influence of 

 Culture in producing these Modifications. Hebrides. Dutch Tulips. 

 Hydrangia. Effect of Soil on Variations. Of Grafting. Of Lop- 

 ping. Of Pruning Trees. Resinous Tree*. Green-house Plants. 

 Fruit Trees. - - - 288 



CONVERSATION XXVI. 



ON THE DEGENERATION AND THE DISEASES OF PLANTS. 



Degeneration of Organs producing Monstrosities. Monopetals. Failure, 

 of Seed. Double-blossomed Flowers, Conversion of Petioles into 



