820 T he Amerwan Naturaust. . [September, 
upon the hopefulness of attaining correct biological conceptions 
through strictly mathematical processes. He laid down the 
principle that *the predominance of certain families of plants 
determines the character of a landscape, and whether the aspect 
of the country is desolate or luxuriant, or smiling and majes- 
tic ;" and further, that “the predominance of a particular species, 
as to the number of individuals —the mass,—or, on the other 
hand, the lack of certain species, may give to a region a pecu- 
liar physiognomy." Connecting his thought, in the usual way, 
with man and his welfare, he says: “ Grasses forming extended 
savannahs, or the abundance of fruit-yielding palms, or social 
coniferous trees, have respectively exerted a powerful influence 
on the material condition, manners, and character of nations, and 
on the more or less rapid development of their prosperity." 
From this point of view, then, the first thing to be undertaken 
in the study of the geography of plants was to bring out the con- 
spicuous characteristics of the flora of a given region by deter- 
mining the number of species of a particular family, as compared 
with the whole number of species constituting the flora of the 
region in question. Asa single specimen of the laborious com- 
parisons carried out by him may be cited his tabulated statements 
of the estimated preponderance of various families of plants in 
the north temperate zone? | 
It is unnecessary to say that he did not possess, at that time, 
sufficient data for making such estimates more than approximate. 
Nor if they had been exact would they have brought out the real 
principles involved. Humboldt himself seems to have felt this, 
and to have groped almost painfully after the solution of the 
problem. “ The forms of organic beings," he says, " are recipro- 
cally dependent on one another. Such is the unity of nature, 
that these forms limit each other in obedience to laws which are 
probably connected with long periods of time.” He anticipated, 
3 The number of species of several conspicuous families were compared with the whole 
number of species of that zone. Thus: 
Glumaces, j. - Umbellifer®, 75. 
Compositee, }. Amentacez, 
Leguminosze, yy. Cruciferee, ys. 
