4 



%•-. on the Geography of Plants. 249 



remain 32, a number which, with Hoffmann's whole number, 

 affords ^, It may be very well assumed, that the Flora of 

 Germany contains at least 2,600 phanerogamous plants, and 

 that the number of German ferns known at present is 36 — 38 ; 

 therefore tlie proportion of this family to the whole number of 

 phanerogamous plants should be -^ or y^. Many Floras admit 

 likewise cultivated plants, and since, of some families, a con- 

 siderable number, but of ethers only very few are cultivated, 

 there arises in this way another considerable variation. 



The author very justly remarks, p. xiv., that in a comparison 

 of different zones, we can only take into consideration those 

 plants which grow in the plains. It is indeed evident that the 

 result must be fallacious ; if, for example, in South America, we 

 reckon those plants which grow at any considerable height 

 above the surface of the sea, since they, in respect to their 

 habitats, belong to the temperate and frigid zones. From this, 

 however, the author departs, in regard to the respective pro- 

 portions of natural families given for South America, p. xvi., 

 the plants of which these consist not growing in higher lati- 

 tudes, for he says himself: *' Observandum tamen est hos nu- 

 meros vtram distributionem non accuratissime exhibere, quia non 

 temper per plana Zones torridce iter fecimus, sed persape per 

 clivos Andiunij ubi propter decrescentem dtris calorem, diver- 

 sarum regionum Florce se excipere videntur,'* Likewise in the 

 proportions given, p. xiv. for Germany and France, and p xv. 

 for North America ; those plants are not excluded which grow 

 at such an altitude, that they cannot be regarded as belonging 

 to the temperate zone. The superscription to the table, p. xviii., 

 runs thus : ratio plantarum in locis planis provenientium ;" it 

 was therefore to be expected that the plants of the higher re- 

 gions would be excluded. Whereas, we find, with the exception 

 of the Umbelliferce and Crucifera, that the proportions which 

 are given here for the equatorial zone, agree pretty exactly 

 with those mentioned, p. xvi. ; which is in direct contradiction 

 to what he afterwards advances, viz., that, with some exceptions, 

 the respective proportions of the families of plants vary towards 

 the summits of the mountains, in the same manner as upon the 



Vol. X. S 



