INTRODUCTION xi 



culace^, Saxifragacese, Primulaceae, Campanulacese, and 

 Gentianaceae ; in the flora of the Alps the Compositae, 

 Leguminosae, Cruciferae, and Caryophylleae are also 

 very strongly represented. In a paper read before the 

 Linnean Society in 1895, but not yet pubHshed, the 

 highest authority on the flora of the Alps, the late Mr. 

 John Ball, for some years President of the Alpine Club, 

 gives the geographical distribution of every Swiss plant, 

 in tables which are the result of an enormous amount of 

 careful work. He enumerates 2010 species of flowering 

 plants, in addition to 335 sub-species. Of these, 11 17 

 species, or a little over one-half, belong to the upper zone 

 of the Alps. The chain on the southern side of the Rhone 

 Valley is far richer than the Alps of Central and Eastern 

 Switzerland or of Savoy. In an introduction to this 

 paper, Mr. Thiselton-Dyer gives an admirable resume of 

 the views on the origin of the alpine flora advocated 

 by the two highest authorities, M. Alphonse De Candolle 

 and Mr. John Ball. Both these experts agree in a recog- 

 nition of the fact that " there is an element of great anti- 

 quity in the alpine flora, which cannot be simply accounted 

 for by a migration from the north during the glacial 

 epoch." De Candolle points out that some of the most 

 ancient fragments of the alpine flora, species of Primula^ 

 Pedicularis, and Oxytropis^ are now to be found only on 

 the southern slopes of the Alps, existing neither in the 

 interior of Switzerland nor in the North of Europe. 

 Furthermore, the alpine species of Campanula peculiar 

 to Mont Cenis, the Simplon, and the neighbouring valleys, 

 are not related to arctic species, but to those of moun- 

 tain chains to the eastward. Mr. Ball further states 

 that of the species included in the alpine flora, 17 per 



