determine ten thousand species of plants according to the received models, but the man of clear logic and wide deductions from his lore. Botany must be conceived as a distinct branch of general thought; otherwise it is worthless, and its herbarium may rot unnoticed in the corner and its discoveries be the outcome of blind hazard. Schleiden himself had no perception of the great idea that Darwin was to bring into his province afterwards—the idea of the variability of species and of evolution, which brought to a critical stage the question whether the botanist was to be merely a subordinate museum-secretary or a creative thinker, a prophet of nature to whom plants would be part of a general philosophy, a part of God in the ideal sense of evolution. Yet Schleiden’s simple warning cry made a deep impression on many of the young men especially. There was a note of aspiration in it, an assurance that they were waiting for a sun that _must_ rise somewhere. He was a master of language. There was the stuff of the poet in him. His works strayed out far beyond the range of his own province. Haeckel himself did the same work in later years. It is no wonder that Schleiden had a magical influence over him. In this case, indeed, it seemed as if the attraction was to determine his own career. Schleiden taught botany at Jena University. Haeckel was still in the higher forms of his school at Merseburg, and remained there when his father resigned his position in the State service, and eventually removed to Berlin. At this time the ardent botanist decided to adopt the science of plants as his life-study when his final examination was over. Schleiden would teach him how to combine philosophy with botany. Then he would try to roam over the world as a practical botanist and visit the far-off zones where Mother Earth poured out her cornucopia of forms so generously. While still in the higher form at school he made a preliminary visit to Jena. Everything seemed so pleasant and charming. He made the journey on foot. These long walks have always been his pride—to start out like a travelling scholar, with hardly anything in his pocket, to live on bread and water, and sleep in the hay at night; but to enjoy to the full all the incomparable delights that the great magician, nature, provides for the faithful novice—scenery, beautiful orchids, thoughts of God, Goethe, and the world. It was in 1849 that he visited Jena. He has described it himself: “After I had reverently admired the Goethe-room in the castle of Dornburg, I wandered, on a hot July day, over the shady meadows to Jena, singing lustily with my gay comrades. As I entered the venerable old market-place I found a troop of lively students in front of the Burgkeller, with coloured caps and long pipes, singing, and drinking the famous Lichtenhain beer from wooden tankards. It made a great impression on me, and as I took a tankard with them I made up my mind that I would some day be one of them.”