I IO 
THE TANGANYIKA PROBLEM. 
independent of the natural environment of forest trees, but 
who acted in a persistent manner, clearing away the bushes 
and brambles off the lawns, in which he planted great 
trees and little trees, so that their limbs and foliage could 
grow luxuriantly and be seen. Moreover, in England, 
when such a park has once been formed by the agency of 
man, it is absolutely necessary that the operations of the 
gardener shall go on and continue, or the park will 
inevitably and quickly lose its artificial characters. Thorns 
and briars and bushes will quickly spring up upon the 
grass, and in a few years the park will have gone back 
again to what we are accustomed here to regard as a 
state of nature ; or, in other words, it will have become 
converted into a trackless waste of old and young jungle. 
In England or Europe a park-land is thus an artificial 
product, and is an impossibility, unless there is someone 
ready and willing to hold the natural tendencies of the 
vegetation in check. In tropical Africa, on the other hand, 
precisely the same floral arrangement is produced, but no 
human agency has had anything to do with it ; and the 
existence of these natural park-lands presents us with a 
ready-made and an extraordinary puzzle, which it is 
interesting to try to understand. 
In attempting to account for the appearance of park- 
lands, the most natural supposition to make is, of course, 
that of inequality of dampness or character of the soil, 
which is sufficient to allow some kinds of trees to grow in 
one place, some in another, and grass in between ; but 
although this view of the matter looks very nice and 
promising at first sight, its value is absolutely destroyed 
by the facts of the case. I have on several occasions, 
when in a park-land, set my men to trench and dig in 
different directions, and then examined the soil, with the 
