BOTANY. 215 



whatever. It is, however, quite certain that it 

 must have come from somewhere, unless it origi- 

 nated in the region ; and therefore one is obliged 

 to suppose that it arrived either from South 

 America or some part of Asia, or from the Cape 

 of Good Hope. Of these the most probable is 

 certainly Asia, and there is a resemblance between 

 the genera of Malaya and those of Congese Africa.* 



I entered and left this region in two places 

 during my route, and in all my experience I have 

 never seen so well-marked a line of distinction. 

 When I came into the Wimi valley, I could in 

 some places have supposed myself near Sierra 

 Leone ; and again, on descending the mountains 

 bordering Tanganyika on their western side, to 

 about 3,500 feet, I immediately noted that I was in 

 a Western Flora. On leaving the lake at Kituta, 

 I found myself at once out of it after ascending 

 not more than 1,000 feet above the level of the 

 lake (i.e., 3,700 feet). 



Now let us consider the Easterly Wet Climate. 

 All along the east coast, beginning at Kilindini, 

 lies a series of river valleys such as the Sabakhi, 

 Eovuma, Zambesi, and Shire, which latter in- 

 cludes Lake Nyassa. These have all of them a 

 very moist, unhealthy, and feverish climate. Their 

 plants are quite different to those of the westerly 

 wet side. Perhaps this can be most easily shown 

 by the statistical method. 



' I believe Professor Oliver holds this view. 



