268 NOTES OF A NATURALIST. 



{S. candidans of botanists), which, with nearly twenty- 

 others, represents that cosmopolitan genus in this 

 region. What light would be thrown on the past 

 history of the vegetable kingdom if we could learn 

 the origin of that vast genus, and the processes by 

 which it has been diffused throughout the world ! 

 Of about nine hundred known species that extend 

 from the Arctic Circle to high southern latitudes, and 

 from the highest zone of the Alps, the Himalayas 

 and the Andes, to the low country of Brazil and the 

 scorching plains of North and South Africa, the great 

 majority are confined to small areas, and are unusually 

 constant in structure, thus presenting a marked con- 

 trast to the ordinary rule, dwelt on by Darwin, that 

 among genera that extend over a large portion of 

 earth and have numerous species, the species, or many 

 of them, are themselves widely spread and vary much 

 in form. Neither do we find among the crowd of 

 species many indications of the general tendency to 

 form groups of species nearly allied in appearance 

 and structure within the same geographical area. 

 Many of the very numerous South American species 

 are nearly allied to European and Asiatic forms. Thus 

 in the comparatively small area of Europe we find 

 the representatives of groups characteristic of regions 

 widely separated,, and even in the poverty-stricken 

 flora of Britain such different forms as the common 

 groundsel, the ragwort of neglected fields, and the 

 less common Senecio paludosus, and 6". campestris. 



The day wore on, and yet no steamer appeared. 

 Knowing people began to speculate on the possibility 

 of some accident having delayed her arrival, or sur- 



