Just a few years ago three geologists were encamped on the bottom of the Grand Canyon. They had hiked a considerable distance in studying the varied rock formations and retired early, each cozy in his own sleeping bag. Later two of the men were rudely awakened by the third, who was screaming in terror. He appeared to erupt from his sleeping bag and, picking up a large piece of firewood, pummeled his bed vigorously with it. A chilled snake had crawled into his warm sleeping bag for the night. Fortunately it was a nonpoisonous specimen, and the scientist suffered only from fright. But not all naturalists have gotten off so easily. The following is an account of a more harrowing experience.

In 1949 a group of American scientists set up camp in the jungle hill country of the Canal Zone. They slept in sleeping bags under canvas rain shields. At about midnight one of the men heard a faint rustle near his head, and moments later a large snake slithered across his check. It crawled into his sleeping bag, and when it reached his stomach it coiled to spend the night. The man froze instantly with the sound of the first rustle; he suspected the snake was the deadly bushmaster common in the region.

Through the long, dark hours of the night the man remained absolutely motionless, knowing that any movement might mean an agonizing death.

At dawn his companions, who at first chided him for oversleeping, stopped abruptly when they saw his gaunt face and the suspicious bulge in his sleeping bag. One of the Indian guides gently cut open a slit at the foot of the bag and blew cigarette smoke into it. The smoke drifted out of the top of the bag, bringing tears to the eyes of the trapped man as he struggled not to cough or move. This tactic was less than effective, but the crew could think of no other way to motionlessly encourage the snake to wake up and leave.

The snake had now been in the sleeping bag for about twelve hours, during which time the man had not dared to move a muscle. The day warmed rapidly, and the man began to sweat in the bag; finally the snake stirred but settled again.

One of the trapped man's companions carefully removed the overhanging rain shield, allowing the tropical sun to beat directly onto the sleeping bag. By now the man was nearly delirious from the merciless heat, and almost every muscle was cramped; still he did not move.

Just when he was on the verge of losing consciousness, the bulge in his stomach region moved. The heat had finally become too much for the visitor, so it crawled out of the sleeping bag and headed for the shade. It was promptly killed and held up for all to see — a large, deadly bushmaster.

Ironically, now that he could move again, the man passed out. He was revived and carried to the hospital for treatment. For him the ordeal was over, but as soon as he recovered he resigned his job and left the Central American jungle. Very determined never to repeat such a night of terror, he relocated to a desert environment.

From the book: 
Our Fascinating Earth