THE TANGANYIKA PROBLEM. n 9 
may not be clue, as we have hitherto been in the habit of 
supposing, to the struggle for existence between contending 
species, but entirely to the sorting influence of a progressive 
physical change to which the biological phenomena are 
related in a manner of a perpetually responding reflection. 
The struggle for existence betw-een contending species has 
had nothing to do with the chief features of the flora ol 
vast areas in the African interior which are now covered 
with natural parks. 
