When I contemplated going on this trip the first thing I did was to get in touch with Dr. Frank M. Chapman of the American Museum. I wanted to get from him information as to what we could do down there and whether it would be worth while for the Museum to send a couple of naturalists with me. On any trip of this kind—on any kind of a trip I have ever taken—the worth of the trip depends not upon one man but upon the work done by several men in coöperation. This journey to South America would have been not worth the taking, had it not been for the two naturalists from the American Museum who were with me, and for the Brazilian officers skilled in cartographical work who joined the expedition.
I thought of making the trip a zoölogical one only, when I started from New York, but when I reached Rio Janeiro the Minister of Foreign Affairs, Mr. Lauro Müller, whom I had known before, told me that he thought there was a chance of our doing a piece of geographical work of importance. In the course of the work of the telegraph commission under Colonel Rondon, a Brazilian engineer, there had been discovered the headwaters of a river running north through the center of Brazil. To go down that river and put it on the map would be interesting, but he wanted to tell me that one cannot guarantee what may happen on unknown rivers—there might be some surprises before we got through. Of course we jumped at the chance, and at once arranged to meet Colonel Rondon and his assistants at the head of the Paraguay, to go down from there with them.
We touched at Bahia and Rio Janeiro and then came down by railway across southern Brazil and Uruguay to Buenos Aires and went through the Argentine over to Chili. We traveled south through Chili and then crossed the Andes. That sounds a very elaborate thing to do, but as a matter of fact it was pure pleasure. It was a wonderful trip. The pass through which we crossed was like the Yosemite, with snowcapped volcanic mountains all about. Afterward we went across Patagonia by automobile and then started up the Paraguay. Our work did not begin until we were inside the Tropic of Capricorn. We took mules at Tapirapoan and went up through the high central plateau of Brazil—not a fertile country but I have no question but that great industrial communities will grow up there.
The hard work on the unknown river came during the first six weeks. In those forty-two days we made only an average of about a mile and a half a day and toward the end we were not eating any more than was necessary and that was largely monkey and parrot. The parrots were pretty good when they were not tough but I can assure Mr. Hornaday that he could leave me alone in the monkey cage at the New York Zoölogical Gardens with perfect safety.
Both of the naturalists who were with me and I myself were interested primarily in mammalogy and ornithology. We were not entomologists and studied only those insects that forced themselves upon our attention. There were two or three types that were welcome. The butterflies were really wonderful. I shall never forget the spectacle in certain places on the Unknown River where great azure blue butterflies would fly about up and down through the glade or over the river. Some of the noises made by insects were extraordinary. One insect similar to a katydid made a noise that ended with a sound like a steamboat whistle.
We found the mosquitoes bad in only two or three places. On the Paraguay marshes there were practically no mosquitoes. In that great marsh country where I should suppose mosquitoes would swarm, there were scarcely any. Our trouble was chiefly with gnats. These little flies were at times a serious nuisance. We had to wear gauntlets and helmets and we had to tie the bottom of our trouser legs. When we stopped on one occasion to build canoes, two or three of our camaradas were so crippled with the bites of the gnats that they could hardly walk. The wasps and stinging bees were also very obnoxious and at times fairly dangerous. There were ants we called foraging ants that moved in dense columns and killed every living thing that could not get out of the way. If an animal is picketed in the line of march of these foraging ants, they are likely to kill it in short time.
There is also a peculiar ant called the leaf ant which doesn't eat a man but devours his possessions instead. I met with a tragedy one night myself. We had come down the Unknown River and had lost two or three canoes and had to portage whatever we had over the mountain. We had to throw away everything that was not absolutely necessary. I reduced my own baggage to one change of clothing. We got into camp late and Cherrie and I had our two cots close together and did not get the fly up until after dark. My helmet had an inside lining of green and I had worn a red handkerchief around my neck. At night I put my spectacles and the handkerchief in the hat. The next morning I looked out of bed preparing to get my spectacles. I saw a red and green line. It was moving. There was a procession of these leaf-bearing ants with sections of my handkerchief and hat. I had had one spare pair of socks and one spare set of underclothing and I needed them both. By morning I had part of one sock and the leg and waistband of the underwear and that was all. It is amusing to look back at but it was not amusing at the time.
The most interesting fish that we became acquainted with was called the "cannibal fish," the "man-eating fish." It is about the size of our shad with a heavily undershot jaw and very sharp teeth. So far as I know, it is the only fish in the world that attacks singly or in shoals animals much larger than itself. Cannibal fishes swarm in most of the rivers of the region we passed through, in most places not very dangerous, in others having the custom of attacking man or animals, so that it is dangerous for anyone to go into the water. Blood maddens them. If a duck is shot, they will pull it to pieces in a very few minutes.
This side of Corumba a boy who had been in swimming was attacked in midstream by these fishes and before relief could get to him, he had not only been killed but half eaten. Two members of our party suffered from them. Colonel Rondon after carefully examining a certain spot in the river went into the water and one of these fishes bit off his little toe. On another occasion on the Unknown River, Mr. Cherrie went into the water thinking he could take his bath right near shore and one of the fish bit a piece out of his leg.
One of the most extraordinary things we saw was this. On one occasion one of us shot a crocodile. It rushed back into the water. The fish attacked it at once and they drove that crocodile out of the water back to the men on the bank. It was less afraid of the men than of the fish.
We were interested one day in a certain big catfish, like any other big catfish except that it had a monkey inside of it. I had never heard that a catfish could catch monkeys but it proved to be a fact. The catfish lives at the bottom of the water. The monkeys come down on the ends of branches to drink and it seems to be no uncommon thing for the fish to come to the surface and attack the monkey as it stoops to drink. Our Brazilian friends told us that in the Amazon there is a gigantic catfish nine feet long. The natives are more afraid of it than of the crocodile because the crocodile can be seen but the catfish is never seen until too late. In the villages, poles are stacked in the water so that women can get their jars filled with water, these stockades of poles keeping out the giant crocodile and catfish. I had never seen in any book any allusions to the fact that there is a man-eating fish of this type in the Amazon.