42 
Transactions of the Boyal Society of South Africa. 
Helichrysum sp. ; six of Lobelia Erinus ; and single specimens of Tragia 
■durhanensis, Commeliiia Krebsiana var., Hibiscus Trionum, Geranium 
ornitho'podium, Pellaea hastata, and a small plant of Acacia horrida. 
In the lower lying areas of the grass -savannah is found an association 
dominated by Cyperaceae. Casual inspection of this association leads to the 
supposition that it may be determined by higher water content of the soil, 
but, so far as observations go, this is, in point of fact, not the case. 
Determinations of the water content were made from samples collected in 
four selected localities between 3 and 5 p.m. on December 26, 1911, the last 
rainfall having been on December 18 and 19 (negligible amount on the 
second day). Other determinations made on December 20 showed a fall of 
approximately 10 per cent, in water content between December 20 and 
December 26. In each case a cylinder of soil was dug out to a depth of six 
inches, quickly powdered, the larger stones, roots, etc., removed, and a 
suitable quantity transferred to a tin with an air-tight lid. The tin and 
contents were weighed within about three hours, and the soil was then dried 
at a moderate temperature. Exactly the same procedure was followed in 
each case, and the water content is calculated as percentage weight in dry 
soil. 
I. Taken close to the quadrant described above, selected as typical of the 
savannah dominated by Eriaiithus Sorghum. The soil was found to contain 
17*77 per cent, of water. 
II. Taken about 60 yards from I, higher up a slope of about 1 in 10, 
and amongst tall " Dobo " grass, Cym])oj)ogo7i marginatus, var. validus, 
mentioned above, as the alternative dominant of this formation. This 
record is also in typical savannah, but the grasses were considerably taller 
than in the place where sample I was taken, so that the ground was 
probably more sheltered, and evaporation less rapid. The soil was found to 
contain 21-17 per cent, of water. 
III. Taken amongst Cyperaceae, about 30 yards north of a fairly large 
pool of very slowly running water, and about 10-15 ft. above the water 
level of the pool. The soil was a trifle looser than in samples I and II, and 
possibly contained a slightly smaller proportion of clay ; it was, however, of 
the same general type. The vegetation being less high and dense, evapora- 
tion may have been more rapid. This sample contained 16*28 per cent, of 
water. 
IV. Taken in the forest, about 25 yards from its junction with the 
savannah. The forest was fairly open at the spot chosen, but with some 
tall trees and a fair amount of undergrowth. The sample contained 20*80 
per cent, of water. 
It is estimated that the probable error in these determinations does not 
exceed 0*5 per cent. 
