EXCURSION ON THE RIO NEGRO. 339 
or peccan-nut trees, so readily distinguished on the lower 
course of the Mississippi, or the different kinds of oaks, 
birches, beeches, or walnut-trees which attract observation 
when sailing along the shores of our Northern lakes. It 
seems, however, impossible to discriminate between all the 
trees of this wonderful Amazonian forest ; partly because 
they grow in such heterogeneous associations. In the 
temperate zone we have oak-forests, pine-forests, birch, 
beech, and maple woods, the same kinds of trees con- 
gregating together on one soil. Not so here ; there is 
the most extraordinary diversity in the combination of 
plants, and it is a very rare thing to see the soil occu- 
pied for any extent by the same kind of tree. A large 
number of the trees forming these forests are still unknown 
to science, and yet the Indians, those practical botanists 
and zoologists, are well acquainted, not only with their 
external appearance, but also with their various properties. 
So intimate is their practical knowledge of the natural ob- 
jects about them, that I believe it would greatly contribute 
to the progress of science if a systematic record were made 
of all the information thus scattered through the land ; an 
encyclopaedia of the woods, as it were, taken down from 
the tribes which inhabit them. I think it would be no bad 
way of collecting, to go from settlement to settlement, send- 
ing the Indians out to gather all the plants they know, to 
dry and label them with the names applied to them in the 
locality, and writing out, under the heads of these names, 
all that may thus be ascertained of their medicinal and 
otherwise useful properties, as well as their botanical char- 
acter. A critical examination of these collections would at 
once correct the information thus obtained, especially if the 
person intrusted with the care of gathering these materials 
