“Colonizability” of Africa by Sir Harry Johnston.
Red: Healthy colonizable Africa, where European races may be expected to become in time the prevailing type, where essentially European states may be formed.
Yellow: Fairly healthy Africa; but where unfavourable conditions of soil or water supply, or the prior establishment of warlike or enlightened native races or other causes, may effectually prevent European colonization.
Gray: Unhealthy but exploitable Africa; impossible for European colonization, but for the most part of igreat commercial value and inhabited by fairly docile, governable races; the Africa of the trader and planter and of despotic European control.
Black: Extremely unhealthy Africa.