48 Baron Humboldt the Laxvs which are observed 
what unexpected. The mass of facts is increased by the very 
desire of invalidating or corroborating the results to which I 
have applied myself. It is thus that, in the progress of the phy- 
sical sciences, general ideas, which at first have only been de- 
duced from a small number of facts, compel observers to mul- 
tiply the partial results. Enriched by these materials, profiting 
daily by whatever truth or utility is contained in the most severe 
criticism of my works, I have been enabled to give to the nu- 
merical results of which the table of vegetable forms consists, a 
degree of exactness which I have not till now been able to at- 
tain. It is in the nature of these researches, that we are not able 
to rectify the co-efficients otherwise than progressively, in propor- 
tion as the observations accumulate. I have attended here only 
to the general development of principles. As this kind of bo- 
tanical arithmetic demands more minute discussions of the pro- 
portions of each family of vegetables to the whole mass of phae- 
iiogamous plants, I have thrown together these discussions in 
the notes which I have published separately 
We may foresee, that the labour which I have bestowed on 
the families of plants, will one day be applied with success to 
most of the classes of vertebral animals. The immense collec- 
tions which are to be seen at Paris, in the Museum of Natural 
History, show that we are already acquainted with nearly 56,000 
species of Plants, cryptogamous and phaenogamous ; 44,000 In- 
sects^ 2500 Fishes ; 700 Reptiles ; 4000 Birds ; and 500 species 
of Mammalia. Agreeably to the inquiries which M, Valenciennes 
and I have made, there exist in Europe alone nearly 80 Mam- 
malia, 400 Birds, and 30 Reptiles : it follows, that, in this nor- 
thern temperate zone, there are five times as many species of 
Birds as of Mammalia, as there are (in Europe) five times as 
many Compositse as Amentaceae and Coniferae ; five times as many 
Leguminosas as Orchideae and Euphorbiaceae. The beautiful 
collections lately brought from the Cape of Good Hope by M. 
He Lalande prove, (if we compare them with the works of 
MM. Temminik and Le Vaillant), that in that part of the sou- 
thern temperate zone, the Mammalia are to the Birds in the 
• See Dictionnaire des Sciences Naturelles, arranged by the Professors of the 
Garden of Plants, vol. xviii. p. 423, — 436. 
