1899 | VEGETATION OF TROPICAL AMERICA 17 
grasslands I have never seen anywhere, with the exception of a 
very brief time in the early spring. 
The same is true in reference to the vegetation of the forest 
ground. Nowhere have I seen such soft, swelling, and fresh 
green moss carpets as those in our woods of coniferous trees, 
and nowhere have I seen such a flowering woodland as that of 
our beech woods in the early spring. The fact is that wherever 
in the tropics the rainfall is small and the ground dry, the vege- 
tation develops itself either as savannas, or as dry thorny cheer- 
less scrub, or as dry forests poor in mold, though rich in 
lianas, bushes, and small trees, because of which they are almost 
impenetrable; or the country becomes, as in the highland of 
Mexico, almost a desert. But if water is at hand, especially 
water in the soil, there all sorts of trees, bushes, and herbs 
will spring up luxuriantly, in an abundance and with a foliage 
unknown in the north. In consequence of the abundance of 
water either a forest or a marsh vegetation develops itself. If 
the soil is especially rich in water, there will be a marsh, with 
high grassy plants and other herbs, bushes, and even trees, a 
vegetation through which it is anything but easy and agreeable 
to walk, and where, moreover, malarial fevers abide. But if the 
moisture of the soil suits a forest, one with impenetrable masses 
of trees, bushes, and lianas will be formed. In the dim light of 
the forest floor, which is covered with leaves and dead branches, 
mosses grow only with difficulty. On the stems of the trees 
they struggle with ferns, orchids, and other epiphytes as to which 
shall keep the place, and they are even forced to migrate to the 
leaves; but thick, soft, green moss carpets are never found. 
Now, with your permission, I shall conclude these descrip- 
tions. I have wished to throw into relief at once how historical 
as well as physical factors enter into and are determining the 
nature of vegetation in a country, and how, in my view, the 
historical factors are of importance as to the richness in species, 
while the physical factors are especially important in determin- 
ing the physiognomy of the species and of the vegetation as a 
whole. And at the same time, I have desired to draw forth 
