10 SAVAGE SUDAN 



there are genera conspicuously indigenous to the northern 

 half of the continent. Gazelles, for example, begin at the 

 Mediterranean, abound most in Ethiopia, but peter out 

 shortly after passing the Equator. The Cob family also 

 (Adenota\ together with the little dikdiks, seem typically 

 though not quite exclusively Ethiopian. 



While yet busy with these chapters, I find that Darwin 

 long ago summed up this matter thus (Origin of Species, 

 3rd ed., p. 5): "Who can explain why one species 

 ranges widely and is very numerous, while another allied 

 species has a narrow range and is rare?" Again, at 

 p. 41 1 : " We cannot hope to explain such facts, until we 

 can say why . . . one species ranges twice or thrice as far, 

 and is twice or thrice as common as another species 

 within their own home." 



Surely after that no more need be said on the subject, 

 save only that while fresh material has been accumulating 

 during seventy or eighty years, no fresh light has been 

 thrown on the problems that puzzled Darwin. 



BIRD-LIFE in detail is described throughout this book. 

 The outstanding feature in Sudanese ornithology is that 

 the sequence of bird-life throughout the year yet remains 

 unascertained more so, probably, than that of any other 

 explored region on earth. No fault attaches to orni- 

 thologists : the cause lies in local climatic conditions, and 

 in those physical obstacles which forbid exploration of 

 the interior during spring, summer, and early autumn. 

 . Those periods, needless to say, normally form the 

 seasons of chiefest interest ; for it is during their breeding- 

 time that birds reveal their secrets and when ornithologists 

 garner harvests. In the Sudan no such harvests are 

 possible. Nature forbids. In winter we can travel afar 

 throughout the country and can see all there is to be 

 seen without difficulty. But no sooner has spring come 

 than torrential rains and the swollen Nile quadrupled 

 in volume by Abyssinian floods transform the lower 

 levels into one vast swamp, submerged and impassable 



