From Ratisbon down we had met occasional freight steamers and tow-boats, and at Passau saw our first passenger steamers--comfortable little craft, which make the popular trip from this place to Linz, fifty-six miles below, in about four hours. The right bank of the Danube below the mouth of the Inn belongs to Austria, and the left bank, for fifteen miles or so, to Bavaria. The Austrian customs-station on the river is at a little hamlet called Engelhardszell, and just above this place the frontier line is marked by a peculiar isolated rock in mid-stream, surmounted by a shrine and crucifix and the rude figure of a saint. We were obliged to go ashore at Engelhardszell to pay river toll on our canoes, and, notwithstanding our strange appearance, each barefooted and sunburned, we met with the greatest civility and courtesy, and paid our sixteen kreutzers (eight cents) apiece without a murmur. Below the frontier the river narrows to half its width, and the speed of the current increases in proportion. The average fall per mile is also much greater in this part of the river than it is from Ulm to this point. From Ulm to Ratisbon the average fall per mile is 1.5 feet; from Ratisbon to Passau, 0.625; from Passau to Linz, 2.5, from Linz to Grein, 2.8, and from Grein to Vienna, 2.876. The flora has varied somewhat since the last reference was made to the botanist’s note-book, and the information on the subject is sure to be interesting: “Below Weltenburg there are pinks and other rock flowers ... and at Kelheim, climbing to the Befreiungshalle, I found a herbaceous clematis with flowers like flammula, or erecta, and with glaucous leaves. The river-banks are mostly devoid of flowers, but on a shingly beach below Ratisbon, where we camped, I noticed a yellow sedum and a dwarf phlox, not in flower. Lower down, when getting near the hills, there were large patches of pink coronilla and a pale yellow mullen, also willow-herb and a white cruciferous plant. “The high, woody hills below Passau are almost entirely covered with beech and pine, but round the houses near the river are walnuts, plums, cherry, and other trees. On the rocks grows a genista with slender twigs and a spike of yellow blossoms, and there are patches of evening-primroses in the more open places. Though vines, hops, and other tender crops grow well, the flora has quite a subalpine character, and the houses are often like Swiss chalets. “In the woods behind our camp, opposite Rannariedl, I noticed pyrola, hepatica, lady-fern, and oak and beech fern, _Spiræa aruncus_, Solomon’s-seal, lactuca, and a fine campanula. In a meadow where we camped the next day were [Illustration: Grein, from the Camp. July 6, 1891] herbaceous clematis and lychnis with drooping white flowers and a berry-like seed-pod, _Anthericum ramosum_ and loosestrife.