282 Baron Humboldt on the Laws which are ohsermd 
curate investigation. We do not relinquish the tracing of a iftapj 
when we perceive the sinuosities of rivers, and the irregular foftai 
of coasts. The laws of magnetism become intelligible to him 
who has commenced with tracing the lines of equal inclination and 
declination, and who has compared a great number of observations, 
which, at first sight, might seem contradictory. He who thinks 
that it is not yet time to search the numerical elements of the 
geography of plants, forgets the progressive march by which 
the physical sciences have elevated themselves to determinate 
results. In examining a complicated phenomenon, we com- 
mence with a general scrutiny of the circumstances by which it 
is determined or modified ; but, before discovering certain pro- 
portions, we find, that the first results to which we attend, are 
not sufficiently free from local influence : it is then that we mo- 
dify and correct the numerical elements, and discover the 
regularity in the very effects of partial disturbances. Criti- 
cism exercises itself on whatever has been prematurely announ- 
ced as a general result ; and the spirit of criticism once excited, 
becomes favourable to the investigation of truth, and accelerates 
the progress of human knowledge. 
Acotyledones. Cryptogamous plants (fungi, lichens, mou- 
ses, and ferns) ; Agames celluleuses et vasculaires of M. De- 
candolle. On uniting the plants of the plains with those of 
the mountains, we have found them to be under the tropics J ; 
but their number ought to be much greater. Mr Brown has 
rendered it very probable, that, in the torrid zone, the propor- 
tion is in the plains on the mountains | *. (Congo, p. 5.) 
In the temperate zone, the agamous plants are generally to the 
phaenogamous as 1 ; 2 ; in the frigid zone they attain the same 
number, and often exceed it considerably. 
On dividing the agamous plants into three groups, we observe 
that the ferns are more frequent (the denominator of the frac- 
tion being less) in the frigid zone than in the temperate zone, 
(Berl. Jahrh., bd. i. p. 32.), and the lichens and mosses also in- 
* In this article, the fractions 1) indicate the proportions betv<^een 
the species of a family and the total number of Phsenogamous plants which 
vegetate in the same country. The abbreviations Trop, Temp. Frig., signify 
Tropics or Torrid Zone, Temperate Zone, Frigid Zone. 
