88 In the Heart of Africa 



The original formation of the lake appears, according to 

 our geologists, to be closely connected with the formation of 

 the Virunga volcanoes. At an earlier period a water basin which 

 was united with the present Lake Albert Edward is supposed to 

 have been divided through volcanic action, and then so dammed 

 up that it found an outlet for itself southwards in the shape 

 of the present River Russisi. The harmony which exists between 

 the fossilised molluscs found by Kirschstein in the crustaceous 

 formations and those still found at Lake Albert Edward may 

 be taken as confirming this theory, as well as that the entire 

 riparian land watered by the Rutschuru north of the volcanoes 

 is an old sea-floor ; the fossilised shell banks and numerous sea 

 shingle deposits are sufficient evidence of this. 



We had some little knowledge of the flora and fauna of Lake 

 Kiwu, through statements which Kandt had afforded, who, 

 amongst other material, presented a comprehensive collection of 

 piscifauna to the Zoological Museum of Berlin. It was our 

 duty now to endeavour to augment and complete the observations 

 already made, especially with regard to the lower organisms. 

 As the time at our disposal was comparatively limited, it was 

 naturally not in our power to make a really exhaustive explora- 

 tion of the lake. The biological investigation of a great water 

 basin necessitates months and years according to the degree of 

 thoroughness aimed at ; for it is not only a question of the area 

 to be explored but that the qualitative and quantitative syntheses, 

 which vary according to the days and seasons of the year, 

 necessitate frequent experiments. Thus there are only a few 

 European lakes which we know thoroughly from a biological 

 point of view, and it will be a long time before we shall be in 

 a position to assert this of the African lakes. All our knowledge 

 of them so far can only be termed superficial at the best, and 

 is proportionate to the brief time devoted to their study and 

 the lack of methodical research. Yet these superficial examina- 

 tions are, in their way, very valuable, as they emanate from quite, 

 or nearly, unknown distiicts, and they furnish us at least with 

 knowledge of a general character respecting the regions in 



