INTRODUCTION 3 



essentially with the sequence of fossils embedded in successive Geo- 

 logical Strata : so that the positive evidence of the Rocks supports, 

 so far as it goes, the grouping of Plants by comparison. 



On such grounds as these, Plants may be sorted into five main 

 divisions, each comprising several Classes. They may be tabulated 

 as follows, while examples are given of familiar Plants, illustrating 

 the sort of living organisms which belong to each Class : 



EXAMPLES. CLASS. DIVISION. 



I Seaweeds and Freshwater Weeds - Algae ^ ,< , 



[Mushrooms, Mildews, Moulds - Fungi/ 



fMosses Musci 1 



- Brvophytes. 

 [Liverworts - - Hepaticae ) 



I Ferns - Filicales -~\ 



- Club-Mosses - Lycopodiales j- - Pteridophytes^ 



[Horse-Tails - - Equisetales J 



Pines, Firs, Yew - - Coniferae - - Gymnosperms. 



(Oak, Sunflower, Potato, Bean - Dicotyledons | 



[Grasses, Lilies, Palms - Monocotyledons/ AnglOSpermS ' 



The natural way to study these would doubtless be to start from 

 the simplest and most primitive, and to proceed to those which are 

 more advanced : that is, to follow the course which we believe 

 that Evolution has taken. It is, however, easier to begin the study 

 of the Living Plant from those of larger size, which are already 

 familiar subjects to everyone, than from minute and unfamiliar 

 organisms, which can only be examined microscopically. It will 

 thus be best for us to take the Higher Flowering Plants first, and 

 to hold over the lower organisms to the end. 



One further general statement may be made regarding the Series 

 as thus laid out. It relates to the mode of life of the Plants con- 

 cerned. Many of the Thallophytes are water-growing Plants, such as 

 Seaweeds, and the Algae of freshwater streams and pools, and most 

 of them grow only where abundant moisture is present. The Mosses 

 and Ferns, though they appear as land-living Plants, require external 

 fluid water for completing one essential stage in their life-history: 

 without it they fail. On this ground they may be called the 

 " Amphibians " of the Vegetable Kingdom. But the Seed-Plants 

 are not thus dependent upon external fluid water. The general 

 conclusion follows that Vegetation began in the water, that it spread 

 later to the land, and that it found its climax in the Seed-Bearing 

 Plants of the Present Day. This is the fundamental idea which should 



