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 districts, and they furnish us at least with 
knowledge of a general character respecting the regions in 
