In his sixty-sixth year he felt the “home-sickness” for the tropics once more with such intensity that he quickly made up his mind to go as far as the equator. He left Jena on August 21, 1900, and (after a brief visit to the exhibition at Paris) took ship at Genoa, on September 4th, for Singapore. His beloved Italy had provided part of the cost of the journey. In the previous year the Royal Academy of Science at Turin had awarded him the Bressa prize (consisting of 10,000 lire) on account of his _Systematic Phylogeny_. Once more the tropics revived the great impression made on him in his earlier visit. This time he spent only a few hours in Ceylon, and sailed further south. He landed at Singapore on September 27th, and sixteen days afterwards went on to Java, and thus crossed the equator at last. He enjoyed to the full the charms of the landscape with its volcanoes and virgin forests, during his stay with Treub at Buitenzorg, at Tjibodas, and during his long journey across the greater part of the island. At Tjibodas he celebrated the close of the nineteenth century [German calculation] by painting a fine water-colour of the smoke-canopy over the summit of the volcano Gedeh, touched and gilded by the east rays of the sun on the last day of 1900. On January 23, 1901, he went from Batavia to Sumatra, crossed the Sunda Strait in sight of the famous volcanic ruins of Krakatoa, and spent six weeks in Padang on the south-west coast of Sumatra. This delay was largely involuntary, and due to an injury to his knee, caused by stumbling over a rail during a visit to an engineering establishment; but the time was by no means lost in the middle of such glories. On March 31st he landed in Europe (at Naples) once more, after a safe voyage. The notes he made during his journey yielded another charming work, _Letters from the East Indies and Malaysia_ (1901). His spirit of enterprise is inexhaustible, and still continues. * * * * * Within this frame of his career we have now to study a growth of ideas and a continuance of research that tell of vigour, consistency, and success in every line. It unfolds logically like a great work of art.