ANNOTATIONS AND ADDITIONS. 105 



employed in the work entitled Regni vegetabilis Systema 

 naturale (T. i. p. 128, 396, 439, 464, and 510), and 

 Kunth has carried it out in regard to the whole number of 

 species of Composite at present known (above 3300). It 

 does not show which is the predominant family either in 

 the number of species or in the quantity of individuals as 

 compared with other families ; it merely tells how many of the 

 species of one and the same family are indigenous in each 

 country or each quarter of the world. The results of this 

 method are on the whole more exact, because they are 

 obtained by the careful study of single families without 

 the necessity of being acquainted with ' .& whole number of 

 the phanerogamse belonging to each country. The most 

 varied forms of Ferns, for example, are found between the 

 tropics; it is there, in the tempered heat of moist and 

 shaded places in mountainous islands, that each genu 

 presents the largest number of species : this variety of 

 species in each genus diminishes in passing from the 

 tropical to the temperate zone, and decreases still farther 

 in approaching nearer to the pole. Nevertheless, as in the 

 cold zone in Lapland, for example those plants succeed 

 best which can best resist the cold, so the species of Ferns, 

 although the absolute number is less than in France or 

 Germany, are yet relatively more numerous than in those 

 countries ; i. e. their number bears a greater proportion to 

 the sum total of all the phanerogamous plants of the 

 country. These proportions or ratios, given as above- 

 mentioned by quotients, are in France and Germany -^ and 

 jV* and in Lapland ~. I published numerical ratios of 



