416 Proceedings of the Royal Phystcal Society. 
Few maps have been published illustrating the geographical 
distribution of disease, and, in the one I have constructed, 
I have attempted a somewhat new departure. I 
have divided Africa into eight regions, each having ap- 
proximately the same climatology, and in each of these 
zones I have introduced symbols to show what diseases 
are present. I have also endeavoured, by repeating the 
symbols, to show the prevalence or the importance of the 
disease. Where one symbol occurs, the disease it represents 
is present in the area; if two symbols are marked on the 
map, the disease is very prevalent; and where three symbols 
occur, the disease is exceedingly rife, or the mortality from 
it excessive. A mere glance at the map will show the 
amount of disease in any area, and the comparative salubrity 
or unhealthiness of a district is at once seen. This, I trust, 
will be useful, especially as the rush to Africa still con- 
tinues, and extensive schemes of colonisation are in the air. 
When the map I have prepared is compared with one 
showing altitude, the reason for the presence or absence of 
many diseases is at once understood. 
After describing the climatology of the various regions 
into which I have divided Africa, and enumerating the 
diseases met with in each area, I have added a short descrip- 
tion of the tropical diseases met with, adding some remarks 
upon their probable origin, their prevention, and treatment. 
This, I think, may be of some use to travellers and others 
visiting the continent. 
Notwithstanding the progress which has been made in 
medicine, in climatology, and in economics, even now we 
know little or nothing as to the effects of climate upon the 
human organism. The subjects of acclimatisation, acclima- 
tion, and the survival of the fittest, are, it is true, touched 
upon by many authors, and it seems to be the idea of many 
that these problems are more or less settled. This, however, 
is not the case. ; 
As a rule, authors writing on Anglo-Saxon extension 
proceed on the @ priori assumption that the Anglo-Saxon 
race can live and thrive more or less all over the world; and 
again, they assume that wheresoever this race may dwell 
