the Vegetation of a Country. 4^19 



and 500 to each family, whilst all the separate Floras, even 

 those of large countries, are far from presenting such high 

 numbers. 



This will show how troublesome it is to compare the propor- 

 tions of the species by genus or family, and also the number 

 of species in relation to the surfaces, between countries of very 

 diflferent extent, as for instance between a small island and a 

 continent, an isolated summit or a small alpine zone and a 

 larger subalpine region, or a great northern country. Never- 

 theless these comparisons have been made even by esteemed 

 authors, but it is always necessary to study methods before 

 employing them, and in nothing is this more true than in 

 statistics. 



6. Analogies with other Floras. 



There are other facts to be ascertained besides the resemblances 

 and differences between the vegetation under consideration and 

 that of adjacent countries, or those with an analogous climate. 

 The relations and differences may exist in ail the kinds of 

 characters. We must of course endeavour to lay most stress 

 upon the principal ones, and for this pui-pose it is necessary to 

 acquire fixed ideas as to the relative value of the characters of 

 vegetation. 



II. Relatia^e Value of the characters of Vegetation. 



Some geographical botanists appear to attach the greatest 

 importance to numerical abstractions, probably on account of the 

 precise form of documents of this nature. I cannot adopt their 

 opinion, and precisely because I prefer exact methods, and 

 exactitude does not always consist in prefez'ring numbers to 

 words, but in giving its true importance to every thing and 

 every point of view. 



In endeavouring to comprehend and depict the general vege- 

 tation of a country, I should first direct my attention to the 

 characters which strike everybody, and which constitute the 

 principal features of the picture. These characters may some- 

 times be expressed by figures, and then it is advisable to take 

 advantage of them ; but this is not always the case. The ordi- 

 nary forms of language, if they express matters of greater 

 importance, appear to me to be preferable to numerical characters 

 of the second or third order. 



The general division of the soil, into marshes, pasture-land, 

 forests, maritime districts, cultivated lands, &c., appears to me 

 to be the thing which at the first glance furnishes the most 

 just notion of the vegetation of a country. We have not only 

 a physical character, such as the temperature and the humidity 

 of the air, but for the forests and meadows also a botanical 



