When, in the summer of 1868, I prepared for the great journey, of which the following pages contain the description, I was already no novice on African soil. In 1863 I had served an apprenticeship in the art of travelling in the sunny fields of Egypt and Nubia. For months together, in my own boat, I had navigated the Red Sea; and it was while I was exploring the untraversed mountains by its coasts that I seriously conceived my larger project. My curiosity was particularly attracted towards the district of the independent Bishareen. I had then repeatedly crossed the country between the Nile and the sea, and while sojourning on the lower terraces of the Abyssinian highlands, I had learnt to appreciate the full enchantment of the wonders of nature in Africa. In 1866, passing through Khartoom and Berber, I found my way back again to Egypt. Once entertained, the project of the botanical investigation of these lands resolved itself more and more into the problem of my life. The splendid herbarium, too, which I had carried home as the reward of my labours, obtained though it was at the cost of repeated attacks of fever, contributed to intensify my desire. Altogether the result of my first attempt was an encouragement and happy omen for my success in a second. My experience hitherto was likewise advantageous to me so far as this,—it had afforded opportunity of cultivating the faculty so necessary to every explorer of unknown districts, of correctly generalising from details. Observations and impressions require to be surveyed from a comprehensive point of view, in order that the characteristic features of a country may be represented in their true proportions. Besides this general information which I had practically gained and which I could no more have learnt from books than I could have learnt the foreign habits and modes of thought, I had also acquired that fluency in the Arab vernacular which is indispensable to every traveller, and which, moreover, appears to suffice for the whole of the immense district which is commanded by the Nile and its host of tributaries. [Sidenote: BOTANICAL ARDOUR.]