Shortly after my arrival in Tandjong Selor, fifty Dayaks, mostly Kenyahs, Oma Bakkah, and some Kayans, arrived from distant Apo Kayan on a trading expedition, and I considered this rather fortunate, as it would largely solve the difficult question of prahus and men for my journey up the river. The controleur and the Sultan also co-operated in assisting me to make a start, but when at last all seemed in readiness, the Malays allowed one of our prahus to drift away down toward the sea; after other similar delays I finally began my expedition up the Kayan River.

At the old pasang-grahan near Kaburau, I found that during our two weeks' absence surprising changes had taken place in the vegetation of the immediate surroundings. The narrow path leading from the river up the embankment was now closed by large plants in flower, one species looking like a kind of iris. The grass which we had left completely cut down had grown over twenty centimeters. (Three weeks later it was in bloom.) It was the month of March and several big trees in the surrounding jungle were covered with masses of white blossoms.

It is about 112 kilometres from Tandiong Selor to Long Pangian, our first halting-place, and, as the current of the river is not strong until the last day, the distance may be covered in four days. When low the Kayan River is light greenish-brown, but when high the colour changes to a muddy red-brown with a tinge of yellow. We used the dilapidated pasang-grahans as shelters, but one night we were obliged to camp on the river bank, so I had the tall, coarse grass cut down on the embankment, which was a few metres higher than the beach. Underneath the tall growth was another kind of grass, growing low and tangled like a mat, which could be disposed of by placing poles under it, lifting it and rolling it back, while at the same time the few roots attaching it to the ground were cut with swords. In less than fifteen minutes I had a safe place for my tent.

The Dayaks, however, who have little to concern them except their prahus, in which is left whatever baggage they may have, as usual slept in the prahus or on the stony beach. During the night the river rose a metre, and some of the men awoke in water. The Chinese mandur, notwithstanding my warnings, had tied his prahu carelessly, and in the middle of the night it drifted off, with lighted lamp and two Dayaks sleeping in it. Luckily some of the others soon discovered the accident and a rescuing party brought it back early in the morning. The "kitchen" had been moved up to my place, and in spite of rain and swollen river we all managed to get breakfast. I had a call from the chief of the near-by kampong, who spoke excellent Malay, and had visited New Guinea twice on Dutch expeditions, once with Doctor Lorenz. One characteristic of the climate which had impressed him much was the snow, which had been very cold for the feet. He was kind enough to send me a present of a young fowl, which was very acceptable.

Long Pangian is a small settlement where ten native soldiers are kept, under the command of a so-called posthouder, in this case a civilized Dayak from the South, who met us at the landing in an immaculate white suit and new tan shoes. It was warmer here toward the end of March than at Tandjong Selor, because there had not been much rain for a month. The soil was therefore hard, and in the middle of the day so heated that after a shower it remained as dry as before. A few Chinamen and Bugis who live here advance rice and dried fish to the Malays to provision expeditions into the utan which last two to three months, receiving in return rubber and damar. The Malays come from lower down on the river, and a good many of them leave their bones in the jungle, dying from beri-beri; others ill with the same disease are barely able to return to Long Pangian, but in three weeks those who do return usually recover sufficiently to walk about again by adopting a diet of katsjang idju, the famous green peas of the East Indies, which counteract the disease. The Malays mix native vegetables with them and thus make a kind of stew.

The rice traded in Borneo is of the ordinary polished variety, almost exclusively from Rangoon, and it is generally supposed that the polishing of the rice is the cause of this illness. The Dutch army in the East seems to have obtained good results by providing the so-called silver-fleeced rice to the soldiers. However, I was told that, in some localities at least, the order had to be rescinded, because the soldiers objected so strongly to that kind of rice. Later, on this same river, I personally experienced a swelling of the ankles, with an acceleration of the heart action, which, on my return to Java, was pronounced by a medical authority to be beri-beri. Without taking any medicine, but simply by the changed habits of life, with a variety of good food, the symptoms soon disappeared.

It is undoubtedly true that the use of polished rice is a cause of beri-beri, because the Dayaks, with their primitive methods of husking, never suffer from this disease, although rice is their staple food. Only on occasions when members of these tribes take part in expeditions to New Guinea, or are confined in prisons, and eat the rice offered of civilization, are they afflicted with this malady. In my own case I am inclined to think that my indisposition at the commencement of my travels in Borneo was largely due to the use of oatmeal from which the husks had been removed. Rolled oats is the proper food.