80 



THE CENTRAL PROYIXCE 



with certain whirlpools amongst the islands in which large canoes can be 

 sucked down. 



Compared to Tanganyika and Nyasa it would seem as though the 

 A'ictoria Xvanza was a relatively shallow lake. The deepest sounding yet 

 taken shows only a maximum depth of 240 feet. On smooth rocks like 

 those of Dolwe Island there is a very well-marked water-line about six 

 feet above the average height of the lake at the present day. In the 

 alisence of any discernilile water-line at a higher elevation, or the traces 

 of ancient beaches, it would seem as though the lake at the present day' 

 was not much more than six feet below the highest level to which it has 

 ever attained. 



In the quiet backwaters of the Victoria Xyanza, where the m.ovement 



69. WATEH-LILIES, VICTORIA XYAXZA: 



of the water into waves is checked by papyrus or sandlianks, marsh 

 vegetation is rapidly taking possession of the shallow water and choking 

 it up. ]\Iany a creek or bay marked as such on the map now presents 

 no water surface to the eye, but is a mass of bright green marsh. There 

 collects first of all in these sheltered waters that pretty floating plant, 

 the Pistia sti:atiotes, the appearance of which is like a small cabbage or 

 lettuce floating on the water. This Pistia sends out horizontal straight 

 roots like cords. From the end of the root springs up another plant, 

 which again shoots out a horizontal root, and so in a short space of time 

 a pool may be covered with a network of Pistia stratiotes, and even be 

 a very pretty object to look at, for this water-plant — allied to the duck- 

 weeds and arums — is of a bright bice green, powdered with a sort of 

 bluish bloom. Then a long grass begins to grow far out into the 



