When I consider the ravages that are made year after year on so large a scale upon the cattle of the Dinka, and the enormous consumption of the Nubians, I confess that it is quite an enigma to me how the supply is not exhausted. Although I am aware that they never kill their cattle, yet the murrain of flies every season decimates their herds; and, besides this, their cows very seldom ever calve more than once, and very frequently remain utterly barren. Observations of this kind somewhat assist us in forming an estimate of the vast numbers of the people, since for the mere oversight and custody of the myriads of cattle there must be multitudes of men corresponding to the hand-to-mouth population of our civilised communities. [Sidenote: EXCURSION TO SUBSIDIARY SERIBAS.] From the 21st of July until the 4th of August I made a tour, which gave me an opportunity of inspecting the subsidiary Seribas of Ghattas. My acquaintance with the country was thus materially enlarged. A march of about four leagues towards the south-west brought me again, by a road which I had not hitherto traversed, to Geer, where the fields of sesame were already in bloom. The sesame in this district all had white blossoms, while in the Nile country it as uniformly blooms with a pale rose-coloured flower, and this is by no means an uncommon feature in the flora of the region. I could exhibit a long list of plants which elsewhere are either red or blue, but here are invariably white; but I could not offer any satisfactory explanation of the circumstance. Like all my other wanderings in the interior, this little excursion was made entirely on foot. To get along through the tall grass was anything but easy. The negroes tread down a sort of gutter, the width of their foot, and along these we made our way, as in a wheel-rut, as best we could. It was quite necessary to keep one’s steps verging inwards. Occasionally these gutters change their character and become water-courses, by means of which the adjacent steppes are drained. But the enjoyment of a luxuriant nature, with its perpetual change of scene, and the charms of novelty which presented themselves in the foliage, compensated richly for a little toil; and day by day practice made the trouble lighter.