1866.] PHYSICAL GEOGRAPHY. 1 1 3 



of a loathsome disease derived direct from the Arabs. 

 Eaised patches of scab of circular form disfigure the face 

 and neck as well as other parts. His brother begged me to 

 see him and administer some remedy for the same complaint. 

 He is at a village a little way off, and though sent for, was 

 too ill to come or to be carried. The tribe is of Babisa 

 origin. Many of these people had gone to the coast as 

 traders, and returning with arms and ammunition joined 

 the Waiyau in their forays on the Manganja, and eventually 

 set themselves up as an independent tribe. The women 

 do not wear the lip-ring, though the majority of them are 

 Waiyau. They cultivate largely, and have plenty to eat. 

 They have cattle, but do not milk them. 



The bogs, or earthen sponges,* of this country occupy a 

 most important part in its physical geography, and pro- 

 bably explain the annual inundations of most of the rivers. 

 Wherever a plain sloping towards a narrow opening in hills 

 or higher ground exists, there we have the conditions 

 requisite for the formation of an African sponge. The 

 vegetation, not being of a heathy or peat-forming kind, falls 

 down, rots, and then forms rich black loam. In many cases a 

 mass of this loam, two or three feet thick, rests on a bed of 

 pure river sand, which is revealed by crabs and other aquatic 

 animals bringing it to the surface. At present, in the dry 

 season, the black loam is cracked in all directions, and the 

 cracks are often as much as three inches wide, and very 

 deep. The whole surface has now fallen down, and rests on 

 the sand, but when the rains come, the first supply is nearly 

 all absorbed in the sand. The black loam forms soft slush, 

 and floats on the sand. The narrow opening prevents it from 

 moving off in a landslip, but an oozing spring rises at that 



* Dr. Livingstone's description of the " Sponge " will stand the reader 

 in good stead when he comes to the constant mention of these obstructions 

 in the later travels towards the north. — En. 



VOL. I. I 



